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Special Issue "Advanced Sensors for Toxins"

A special issue of Toxins (ISSN 2072-6651).

Deadline for manuscript submissions: closed (30 September 2018)

Special Issue Editors

Guest Editor
Prof. Dr. Jean-Louis Marty

Laboratoire BAE, Bâtiment S, Université de Perpignan Via Domitia, 52 Av Paul Alduy 66860 Perpignan cedex France
Website | E-Mail
Interests: Electrochemical and optical biosensors; aptasensors for food and environmental control
Guest Editor
Dr. Gaelle Catanante

BAE-LBBM-USR CNRS 3579, Université de Perpignan Via Domitia , 52 avenue paul allude, 66860 Perpignan cedex, France
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Guest Editor
Dr. Akhtar Hayat

Interdisciplinary Research Centre in Biomedical Materials (IRCBM) COMSATS Institute of Information Technology, 54000 Lahore, Pakistan
Website | E-Mail
Interests: nanomaterials; aptamer/aptasensor; immuno-assay/sensors; enzyme-assay/sensors; electrochemical/colorimetric/fluorescence sensors/biosensors; medical/food/environmental applications

Special Issue Information

Dear Colleagues,

Biological toxins are produced by living organisms and are generally toxic at low concentrations. We are aware of the omnipresence and variability of these toxins in many matrices. These toxins are not often monitored, but have the potential to enter the environment, resulting adverse ecological and human health effects. Political, industrial and academic leaders are aware of the urgent need for robust, rapid, and low-cost methods to detect low concentrations of these toxins in various matrices. Many sensors and biosensors have been described in the literature for the detection of numerous toxins. The goal is the development of new sensors “advanced biosensors”. Our objective is to target these advances sensors and biosensors with respect to the mechanism of molecular recognition, material design, and characterization, sensing procedure. We note that, in spite of the promising approaches demonstrated thus far, much work still needs to be done before they become a viable alternative to conventional methods.

Prof. Dr. Jean Louis Marty
Dr. Gaelle Catanante
Dr. Akhtar Hayat
Guest Editors

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 1500 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

  • Sensor
  • Biosensor
  • Biological Toxins
  • Small molecules
  • Electrochemical
  • Optical
  • Gravimetric
  • Portable

Published Papers (9 papers)

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Research

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Open AccessArticle Label-Free Optical Detection of Mycotoxins Using Specific Aptamers Immobilized on Gold Nanostructures
Received: 26 June 2018 / Revised: 12 July 2018 / Accepted: 13 July 2018 / Published: 16 July 2018
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Abstract
This work focuses on the development of the novel label-free optical apta-sensors for detection of mycotoxins. A highly sensitive analytical method of total internal reflection ellipsometry (TIRE) combined with Localized Surface Plasmon Resonance (LSPR) phenomenon in nano-structured gold films was exploited here for
[...] Read more.
This work focuses on the development of the novel label-free optical apta-sensors for detection of mycotoxins. A highly sensitive analytical method of total internal reflection ellipsometry (TIRE) combined with Localized Surface Plasmon Resonance (LSPR) phenomenon in nano-structured gold films was exploited here for the first time for detection of aflatoxin B1 and M1 in direct assay with specific aptamers immobilized on the surface of gold. The achieved detection of low molecular weight molecules, such as aflatoxin B1 and M1, in a wide range of concentrations from 100 ng/mL down to 0.01 ng/mL is remarkable for the LSPR method. The study of binding kinetics of aflatoxin molecules to their respective aptamers using dynamic TIRE measurements yielded the values of affinity constants in the range of 10−8–10−7 mol, which is characteristic for highly specific aptamer/target interactions similar to that for monoclonal antibodies. The effect of aptamers’ DNA chain length on their binding characteristics was analyzed. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Open AccessArticle Mycotoxin Biosensor Based on Optical Planar Waveguide
Received: 19 April 2018 / Revised: 6 June 2018 / Accepted: 25 June 2018 / Published: 3 July 2018
Cited by 1 | PDF Full-text (1608 KB) | HTML Full-text | XML Full-text
Abstract
The research aim of this work is to develop a simple and highly sensitive optical biosensor for detection of mycotoxins. This sensor is built on a planar waveguide operating on the polarization interferometry principle, i.e., detecting a phase shift between p- and s-components
[...] Read more.
The research aim of this work is to develop a simple and highly sensitive optical biosensor for detection of mycotoxins. This sensor is built on a planar waveguide operating on the polarization interferometry principle, i.e., detecting a phase shift between p- and s-components of polarized light developed during the binding of analyte molecules. The operation of the proposed sensor is similar to that of a Mach–Zehnder interferometer, while its design is much simpler and it does not require splitting the waveguide into two arms. The refractive index sensitivity of the polarization interferometer sensor was in the range of 5200 radians per refractive index unit (RIU). Several tests were conducted to detect ochratoxin A (OTA) at different concentrations in direct immunoassay with specific antibodies immobilized in the sensing window. The lowest concentration of OTA of 0.01 ng/mL caused a phase shift of nearly one period. The results obtained prove high sensitivity of the sensors, which are capable of detecting even lower concentrations of mycotoxins at the ppt (part-per-trillion) level. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Open AccessArticle Label-Free G-Quadruplex Aptamer Fluorescence Assay for Ochratoxin A Using a Thioflavin T Probe
Received: 17 April 2018 / Revised: 5 May 2018 / Accepted: 8 May 2018 / Published: 12 May 2018
Cited by 1 | PDF Full-text (2426 KB) | HTML Full-text | XML Full-text
Abstract
Ochratoxin A (OTA) is one of the most common mycotoxins contaminating feed and foodstuffs. Therefore, a great deal of concern is associated with AFB1 toxicity. In this work, a fast and sensitive fluorescence aptamer biosensor has been proposed for the OTA assay. In
[...] Read more.
Ochratoxin A (OTA) is one of the most common mycotoxins contaminating feed and foodstuffs. Therefore, a great deal of concern is associated with AFB1 toxicity. In this work, a fast and sensitive fluorescence aptamer biosensor has been proposed for the OTA assay. In the absence of OTA, the OTA aptamer can form a G-quadruplex structure with thioflavin T (ThT) dye, which results in increased fluorescence. After joining OTA, OTA aptamer combines with OTA and the G-quadruplex can be formed. Only faint fluorescence was finally observed when ThT weakly reacts with the quadruplex. Through this test method, the entire reaction and analysis process of OTA can be completed in 10 min. Under optimal experimental conditions (600 nM OTA-APT, 7 μM ThT, and 3 min incubation time), this proposed assay has a good limit of detection (LOD) of 0.4 ng/mL and shows a good linear relationship within the range of 1.2–200 ng/mL under the best experimental conditions. This method has a high specificity for OTA relative to Ochratoxin B (23%) and Aflatoxin B1 (13%). In addition, the quantitative determination of this method in real samples has been validated using a sample of red wine supplemented with a range of OTA concentrations (1.2 ng/mL, 12 ng/mL, and 40 ng/mL) with recoveries of 96.5% to 107%. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Open AccessArticle Electrochemical Immunosensor for Detection of Aflatoxin B1 Based on Indirect Competitive ELISA
Received: 28 March 2018 / Revised: 3 May 2018 / Accepted: 8 May 2018 / Published: 11 May 2018
Cited by 1 | PDF Full-text (1929 KB) | HTML Full-text | XML Full-text
Abstract
Mycotoxins are the secondary toxic metabolites produced naturally by fungi. Analysis of mycotoxins is essential to minimize the consumption of contaminated food and feed. In this present work, an ultrasensitive electrochemical immunosensor for the detection of aflatoxin B1 (AFB1) was
[...] Read more.
Mycotoxins are the secondary toxic metabolites produced naturally by fungi. Analysis of mycotoxins is essential to minimize the consumption of contaminated food and feed. In this present work, an ultrasensitive electrochemical immunosensor for the detection of aflatoxin B1 (AFB1) was successfully developed based on an indirect competitive enzyme-linked immunosorbent assay (ELISA). Various parameters of ELISA, including antigen–antibody concentration, blocking agents, incubation time, temperature and pH of reagents, were first optimized in a 96-well microtiter plate to study the antigen–antibody interaction and optimize the optimum parameters of the assay. The optimized assay was transferred onto the multi-walled carbon nanotubes/chitosan/screen-printed carbon electrode (MWCNTs/CS/SPCE) by covalent attachment with the aid of 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Competition occurred between aflatoxin B1-bovine serum albumin (AFB1–BSA) and free AFB1 (in peanut sample and standard) for the binding site of a fixed amount of anti-AFB1 antibody. Differential pulse voltammetry (DPV) analysis was used for the detection based on the reduction peak of TMB(ox). The developed immunosensor showed a linear range of 0.0001 to 10 ng/mL with detection limit of 0.3 pg/mL. AFB1 analysis in spiked peanut samples resulted in recoveries between 80% and 127%. The precision of the developed immunosensor was evaluated by RSD values (n = 5) as 4.78% and 2.71% for reproducibility and repeatability, respectively. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Open AccessArticle An Imaging Surface Plasmon Resonance Biosensor Assay for the Detection of T-2 Toxin and Masked T-2 Toxin-3-Glucoside in Wheat
Received: 25 January 2018 / Revised: 2 March 2018 / Accepted: 7 March 2018 / Published: 10 March 2018
Cited by 1 | PDF Full-text (2464 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A sensitive, rapid, and reproducible imaging surface plasmon resonance (iSPR) biosensor assay was developed to detect T-2 toxin and T-2 toxin-3-glucoside (T2-G) in wheat. In this competitive assay, an amplification strategy was used after conjugating a secondary antibody (Ab2) with gold
[...] Read more.
A sensitive, rapid, and reproducible imaging surface plasmon resonance (iSPR) biosensor assay was developed to detect T-2 toxin and T-2 toxin-3-glucoside (T2-G) in wheat. In this competitive assay, an amplification strategy was used after conjugating a secondary antibody (Ab2) with gold nanoparticles. Wheat samples were extracted with a methanol/water mixture (80:20 v/v), then diluted with an equal volume of primary antibody (Ab1) for analysis. Matrix-matched calibration curves were prepared to determine T-2 toxin and T2-G. Recovery studies were conducted at three spiking levels in blank wheat. Mean recoveries ranged from 86 to 90%, with relative standard deviations for repeatability (RSDr) of less than 6%. Limits of detection were 1.2 ng/mL of T-2 toxin and 0.9 ng/mL of T2-G, equivalent to their levels in wheat, of 48 and 36 µg/kg, respectively. The developed iSPR assay was rapid and provided enough sensitivity for the monitoring of T-2 toxin/T2-G in wheat. This is the first iSPR assay useful for detecting the “masked” T2-G in wheat. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Open AccessArticle A Rapid Label-Free Fluorescent Aptasensor PicoGreen-Based Strategy for Aflatoxin B1 Detection in Traditional Chinese Medicines
Received: 8 January 2018 / Revised: 19 February 2018 / Accepted: 26 February 2018 / Published: 28 February 2018
Cited by 1 | PDF Full-text (1917 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Aflatoxin B1 (AFB1) is a very hazardous carcinogen, readily contaminating foodstuffs and traditional Chinese medicines (TCMs) that has inspired increasing health concerns due to dietary exposure. Colloidal nanocrystals have been proposed as optical labels for aptasensor assembly, but these typically
[...] Read more.
Aflatoxin B1 (AFB1) is a very hazardous carcinogen, readily contaminating foodstuffs and traditional Chinese medicines (TCMs) that has inspired increasing health concerns due to dietary exposure. Colloidal nanocrystals have been proposed as optical labels for aptasensor assembly, but these typically require tedious multistep conjugation and suffer from unsatisfactory robustness when used for complex matrices. In the present study, we report a rapid and sensitive method for screening for trace AFB1 levels in TCMs using a label-free fluorescent aptasensor PicoGreen dye-based strategy. Using PicoGreen to selectively measure complementary double-stranded DNA, fluorescence enhancement due to dsDNA is ‘turned off’ in the presence of AFB1 due binding of aptamer target over complementary sequence. Self-assembly of a label-free fluorescent aptasensor based on AFB1 aptamer and PicoGreen dye was performed. Due to competition between the complementary sequence and AFB1 target, this rapid method was capable of highly sensitive and selective screening for AFB1 in five types of TCMs. This proposed approach had a limit of detection as low as 0.1 μg·L−1 and good linearity with a range of 0.1–10 μg·L−1 (0.1–10 ppb). Among the 20 samples tested, 6 batches were found to be contaminated with AFB1 using this method, which was confirmed using sophisticated liquid chromatography-electrospray ionization-tandem mass spectrometry/mass spectrometry analysis. The results of this study indicate the developed method has the potential to be a simple, quick, and sensitive tool for detecting AFB1 in TCMs. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Open AccessArticle An On-Site Simultaneous Semi-Quantification of Aflatoxin B1, Zearalenone, and T-2 Toxin in Maize- and Cereal-Based Feed via Multicolor Immunochromatographic Assay
Received: 9 January 2018 / Revised: 8 February 2018 / Accepted: 15 February 2018 / Published: 17 February 2018
Cited by 2 | PDF Full-text (1366 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Multiple-mycotoxin contamination has been frequently found in the agro-food monitoring due to the coexistence of fungi. However, many determination methods focused on a single mycotoxin, highlighting the demand for on-site determination of multiple mycotoxins in a single run. We develop a multicolor-based immunochromatographic
[...] Read more.
Multiple-mycotoxin contamination has been frequently found in the agro-food monitoring due to the coexistence of fungi. However, many determination methods focused on a single mycotoxin, highlighting the demand for on-site determination of multiple mycotoxins in a single run. We develop a multicolor-based immunochromatographic strip (ICS) for simultaneous determination of aflatoxin B1 (AFB1), zearalenone (ZEN) and T-2 toxin in maize- and cereal-based animal feeds. The nanoparticles with different colors are conjugated with three monoclonal antibodies, which serve as the immunoassay probes. The decrease in color intensity is observed by the naked eyes, providing simultaneous quantification of three mycotoxins. The visible limits of detection for AFB1, ZEN and T-2 are estimated to be 0.5, 2, and 30 ng/mL, respectively. The cut-off values are 1, 10, and 50 ng/mL, respectively. Considerable specificity and stability are found using real samples. The results are in excellent agreement with those from high-performance liquid chromatography/tandem mass spectrometry. The multi-color ICS boasts sensitive and rapid visual differentiation and simultaneous semi-quantification of aflatoxin B1, zearalenone and T-2 toxin in maize- and cereal-based feed samples within 20 min. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Review

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Open AccessReview Designed Strategies for Fluorescence-Based Biosensors for the Detection of Mycotoxins
Received: 23 April 2018 / Revised: 8 May 2018 / Accepted: 8 May 2018 / Published: 11 May 2018
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Abstract
Small molecule toxins such as mycotoxins with low molecular weight are the most widely studied biological toxins. These biological toxins are responsible for food poisoning and have the potential to be used as biological warfare agents at the toxic dose. Due to the
[...] Read more.
Small molecule toxins such as mycotoxins with low molecular weight are the most widely studied biological toxins. These biological toxins are responsible for food poisoning and have the potential to be used as biological warfare agents at the toxic dose. Due to the poisonous nature of mycotoxins, effective analysis techniques for quantifying their toxicity are indispensable. In this context, biosensors have been emerged as a powerful tool to monitors toxins at extremely low level. Recently, biosensors based on fluorescence detection have attained special interest with the incorporation of nanomaterials. This review paper will focus on the development of fluorescence-based biosensors for mycotoxin detection, with particular emphasis on their design as well as properties such as sensitivity and specificity. A number of these fluorescent biosensors have shown promising results in food samples for the detection of mycotoxins, suggesting their future potential for food applications. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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Other

Jump to: Research, Review

Open AccessPerspective Molecular Modeling and Simulation Tools in the Development of Peptide-Based Biosensors for Mycotoxin Detection: Example of Ochratoxin
Toxins 2017, 9(12), 395; https://doi.org/10.3390/toxins9120395
Received: 7 November 2017 / Revised: 28 November 2017 / Accepted: 3 December 2017 / Published: 6 December 2017
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Abstract
Mycotoxin contamination of food and feed is now ubiquitous. Exposures to mycotoxin via contact or ingestion can potentially induce adverse health outcomes. Affordable mycotoxin-monitoring systems are highly desired but are limited by (a) the reliance on technically challenging and costly molecular recognition by
[...] Read more.
Mycotoxin contamination of food and feed is now ubiquitous. Exposures to mycotoxin via contact or ingestion can potentially induce adverse health outcomes. Affordable mycotoxin-monitoring systems are highly desired but are limited by (a) the reliance on technically challenging and costly molecular recognition by immuno-capture technologies; and (b) the lack of predictive tools for directing the optimization of alternative molecular recognition modalities. Our group has been exploring the development of ochratoxin detection and monitoring systems using the peptide NFO4 as the molecular recognition receptor in fluorescence, electrochemical and multimodal biosensors. Using ochratoxin as the model mycotoxin, we share our perspective on addressing the technical challenges involved in biosensor fabrication, namely: (a) peptide receptor design; and (b) performance evaluation. Subsequently, the scope and utility of molecular modeling and simulation (MMS) approaches to address the above challenges are described. Informed and enabled by phage display, the subsequent application of MMS approaches can rationally guide subsequent biomolecular engineering of peptide receptors, including bioconjugation and bioimmobilization approaches to be used in the fabrication of peptide biosensors. MMS approaches thus have the potential to reduce biosensor development cost, extend product life cycle, and facilitate multi-analyte detection of mycotoxins, each of which positively contributes to the overall affordability of mycotoxin biosensor monitoring systems. Full article
(This article belongs to the Special Issue Advanced Sensors for Toxins)
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