Electrochemical determination of T2 toxin by graphite/polyacrylonitrile nanofiber electrode

Electrochemical microfluidic immunosensor with graphene-decorated gold nanoporous for T-2 mycotoxin detection

T-2 is one of the most potent cytotoxic food-borne mycotoxins. In this work, we have developed and characterized an electrochemical microfluidic immunosensor for T-2 toxin quantification in wheat germ samples. T-2 toxin detection was carried out using a competitive immunoassay method based on monoclonal anti-T-2 antibodies immobilized on the poly(methyl methacrylate) (PMMA) microfluidic central channel. The platinum wire working electrode at the end of the channel was in situ modified by a single-step electrodeposition procedure with reduced graphene oxide (rGO)-nanoporous gold (NPG). T-2 toxin in the sample was allowed to compete with T-2-horseradish peroxidase (HRP) conjugated for the specific recognizing sites of immobilized anti-T-2 monoclonal antibodies. The HRP, in the presence of hydrogen peroxide (H2O2), catalyzes the oxidation of 4-tert-butylcatechol (4-TBC), whose back electrochemical reduction was detected on the nanostructured electrode at -0.15 V. Thus, at low T-2 concentrations in the sample, more enzymatically conjugated T-2 will bind to the capture antibodies, and, therefore, a higher current is expected. The detection limits found for electrochemical immunosensor, and commercial ELISA procedure were 0.10 μg kg-1 and 10 μg kg-1, and the intra- and inter-assay coefficients of variation were below 5.35% and 6.87%, respectively. Finally, our microfluidic immunosensor to T-2 toxin will significantly contribute to faster, direct, and secure in situ analysis in agricultural samples.

State-of-the-art nanosensors and kits for the detection of antibiotic residues in milk and dairy products

Antibiotic resistance is increasingly seen as a future concern, but antibiotics are still commonly used in animals, leading to their accumulation in humans through the food chain and posing health risks. The development of nanomaterials has opened up possibilities for creating new sensing strategies to detect antibiotic residues, resulting in the emergence of innovative nanobiosensors with different benefits like rapidity, simplicity, accuracy, sensitivity, specificity, and precision. Therefore, this comprehensive review provides pertinent and current insights into nanomaterials-based electrochemical/optical sensors for the detection of antibitic residues (ANBr) across milk and dairy products. Here, we first discuss the commonly used ANBs in real products, the significance of ANBr, and also their binding/biological properties. Then, we provide an overview of the role of using different nanomaterials on the development of advanced nanobiosensors like fluorescence-based, colorimetric, surface-enhanced Raman scattering, surface plasmon resonance, and several important electrochemical nanobiosensors relying on different kinds of electrodes. The enhancement of ANB electrochemical behavior for detection is also outlined, along with a concise overview of the utilization of (bio)recognition units. Ultimately, this paper offers a perspective on the future concepts of this research field and commercialized nanomaterial-based sensors to help upgrade the sensing techniques for ANBr in dairy products.

Fabrication of a sensitive electrochemical sensor based on hybrid polyamide/chromotropic acid nanofibers electrospun on glassy carbon electrode for Hg2+ sensing in drinking water and canned fish samples

In this study, a new electrochemical sensor was designed based on a hybrid of polyamide (PA) and chromotropic acid (CA) nanofibers electrospun on a glassy carbon electrode (GCE) configured as PANFs-CANFs/GCE. The electrochemical response of this sensor showed an excellent electrochemical activity for the detection of Hg²⁺ ions using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The proposed sensor exhibited the prominent electrocatalytic value of (α = 0.60, Log Ks = 3.45 s^-1 and Γ = 3.30 × 10 ^-9 mmol/cm²) as a result of PANFs-CANFs/GCE response to Hg²⁺ ions. The recommended sensor also demonstrated a linear portion in the calibration curve over the concentration range of 30 to 450 nM with the limit of detection (LOD) and limit of quantitation (LOQ) of 9.98 nM and 29.97 nM, respectively. The fabricated sensor revealed reproducible and repeatable responses with a high level of stability. Therefore, we highly recommend this new electro-spun based sensor for quantifying Hg²⁺ in drinking water and canned fish samples with the accurate and precise results and no side interferences.

AgPdNFs and AuNOs@GO nanocomposites for T-2 toxin detection by catalytic hairpin assembly

T-2 toxin is the most potent and toxic mycotoxin, produced by various Fusarium species that can potentially affect human health, and widely exists in field crops and stored grain. In this work, an electrochemical aptasensor with nonenzymatic signal amplification strategy for the detection of T-2 toxin is presented, using noble metal nanocomposites and catalytic hairpin assembly as signal amplification strategy. Silver palladium nanoflowers and gold octahedron nanoparticles@graphene oxide nanocomposites are used for synergistic amplification of electrical signals. Simultaneously, the catalytic hairpin assembly strategy based on artificial molecular technology was introduced to further amplify the signal. Under optimal conditions, T-2 toxin was measured within a linear concentration range 1 × 10^-2 ~ 1 × 10⁴ pg·mL^-1 with an extremely low detection limit of 6.71 fg·mL^-1. The aptasensor exhibited high sensitivity, good selectivity, satisfactory stability, and excellent reproducibility. Moreover, this method had high accuracy in detecting T-2 toxin in beer sample. The encouraging results show the potential application in foodstuff analysis. A dual signal amplification electrochemical biosensor for the detection of T-2 toxins was constructed, through the signal amplification of noble metal nanomaterials and CHA strategy.

Ni/Ni(OH)2-rGO nanocomposites sensor for the detection of long forgotten mycotoxin, xanthomegnin

Xanthomegnin, a known fungal toxin, secondary metabolite, and pigment diffuses from the dermatophytes has gained attention as local virulence factor because of the mutagenicity, toxicity, cytocidal, and immunosuppressive properties. Not only as a dermatophyte in skin related disorders, the production of xanthomegnin is implicated as a powerful diagnostic marker in patients suffering from ocular mycoses. Incidentally also attributed to death in livestock's majorly by exposing themselves to food-borne fungi like Aspergillus and Penicillium. The production of xanthomegnin in dermetophytic species Trichophyton rubrum, found commonly in infected skin and nails. In this study nickel/nickel hydroxide nanoparticles decorated reduced graphene oxide (Ni/Ni(OH)₂-rGO) modified glassy carbon electrode has been successfully used for non-enzymatic detection of xanthomegnin. The Ni/Ni(OH)₂-rGO composites were synthesized through a simple microwave assisted technique with less harmful reducing agent. The UV-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS), and electrochemical investigations demonstrated the robust formation of the sensor. The sensor exhibited improved electrochemical properties with enhanced electrochemical active area and excellent electrochemical behavior towards xanthomegnin detection with a limit of detection of 0.12 μM. The selectivity, stability, and analytical recovery studies proved the potential use of the sensor for the detection of xanthomegnin in real samples. Further, the sensor successfully detected xanthomegnin produced by the Trichophyton rubrum, the most common superficial fungus, accounting for at least 60% of all superficial fungal infections in humans. Validation studies showed satisfiable and quantifiable amount of xanthomegnin in comparison with common bench mark UV-Vis studies meant for fungal mycotoxin detection.

The effect of gamma irradiation, microwaves, and roasting on aflatoxin levels in pistachio kernels

Pistachio is the second largest non-oil export in Iran. The most important problem in pistachio export is its contamination with aflatoxin. Therefore, this study aimed to evaluate the effects of several physical and chemical methods on the qualitative, qualitative and sensory properties of pistachios from Iran as well as the associated residual aflatoxin levels. This study investigated the effects of roasting (temperature 120 °C for 20 and 40 min), gamma radiation (2.5 and 5 KGy), and microwave (1 and 2 min) methods on pistachios and their qualitative characteristics, including moisture, colour, and sensory properties. In addition, aflatoxin B1 and total aflatoxins were artificially added to pistachios to determine the level of aflatoxin remaining after chemical and physical methods. The results showed that the lowest residual level of aflatoxin B1 was related to combined microwave and irradiation methods. Further, the combined methods showed the lowest total aflatoxins residue so the lowest total aflatoxins residue after chemical contamination of 8 μg/kg aflatoxin was related to the combined methods of 5 KGy irradiations with 2 min of the microwave. In addition, the microwaved and irradiated samples did not differ significantly from the control samples in terms of sensory characteristics (P<0.05). It can be concluded that these methods can be successfully applied without adversely affecting the characteristics of pistachios. Considering the position of pistachios in domestic and global markets, these processes can be used to reduce aflatoxins, improve the quality of pistachios, and increase export.

Fate of aflatoxins M1 and B1 within the period of production and storage of Tarkhineh: A traditional Persian fermented food

The objective of the study was to assess the amount of aflatoxin M1 (AFM1) and aflatoxin B1 (AFB1) during fermentation, drying, and storage of Tarkhineh-a traditional Persian fermented food-over four months. Tarkhineh samples were produced based on a traditional method. Various concentrations of AFB1 (2.5, 5, 7.5, and 10 µg/kg) and AFM1, stood at 0.25, 0.5, 0.75, and 1 µg/kg, were added to Iranian yogurt drink, called doogh, samples. Tarkhineh samples were evaluated for AFB1 and AFM1 on days 0, 2, 6, and 8 and also after drying and four months of storage. In cases of repeatability, recovery, and reproducibility, the high-performance liquid chromatography through fluorescence detector (HPLC-FD) method was successfully done to demonstrate aflatoxins (AFs) in Tarkhineh samples. The fermentation process had a considerable consequence on the reduction in AFM1 and AFB1 as compared to the control group, evidenced by 65.10%-81.20% and 55.80%-74.10%, respectively, after eight days of fermentation (p < .05). The highest reduction in AFB1 existed in samples containing 2.5 µg/kg toxin, followed by 5, 7.5, and 10 µg/kg, respectively. A similar trend was found for AFM1, as the highest concentration was found in samples containing 0.25 µg/kg toxin, followed by 0.5, 0.75, and 1 µg/kg, respectively.

Evaluation of nano-silica, microwave heating, and ultraviolet irradiation effects on zearalenone detoxification in sunflower oils

In the present study, we report three methods of silica nanoparticles (SNPs) as adsorbent, ultraviolet (UV) irradiation, and microwave heating and evaluate their capabilities in reducing and eliminating zearalenone (ZEN). The offered method not only was used for ZEN detoxification, but also greatly enhanced the sensitivity of ZEN measurement. The aim of this study was to evaluate ZEN concentration in sunflower oil samples by high-performance liquid chromatography (HPLC) method. This method was successfully validated for sunflower oil samples while the limit of detection (LOD) method (signal-to-noise ratio of 3:1) was 0.5 μg/l. The acquired removal data with the HPLC method through SNPs were fitted well with Freundlich isotherm, denoting that the multi-layer adsorption took place on the adsorbent. The equilibrium adsorption capacity of ZEN was 61.02 μg/g in an optimum time of 240 min on SNPs. The experimental results were evaluated by the adsorption kinetic model, which specified the adsorption kinetics of ZEN on SNPs, obeying the pseudo-second order model. This model demonstrated that the sorption rate depended on the sorption capacity but not the concentration of the sorbate. Moreover, the method presented to determine ZEN based on the use of SNPs in sunflower oil was accomplished by the adsorption process. Furthermore, the removal efficiencies of ZEN by SNPs, UV irradiation, and microwave heating were compared and obtained to be 92.1, 96.22, and 37.30%, respectively for determined times. These results confirm the removal efficiency of these methods is sensitive enough to ZEN analysis in sunflower oil samples.

Electrospun Mats Based on PVA/NaDDBS/CNx Nanocomposite for Electrochemical Sensing

This study presents a nanocomposite developed with PVA, multiwall carbon nanotubes (CNTs) doped with nitrogen, and NaDDBS, which change the electrical properties of the polymer and its viscosity to be used in electrospinning process for obtaining mats of nano/macro fibers. The proposed nanocomposite was characterized using Fourier transform-infrared and Raman spectroscopy techniques, confirming the presence of the CNxs immersed in the polymer. High-resolution transmission electron microscopy was used to obtain the micrographs that showed the characteristic interplanar distances of the multiwall CNT in the polymeric matrix, with values of 3.63 Å. Finally, the CNx mats were exposed to various aqueous solutions in a potentiostat to demonstrate the effectiveness of the nanofibers for electrochemical analysis. The CNx-induced changes in the electrical properties of the polymer were identified using cyclic voltammograms, while the electrochemical analysis revealed supercapacitor behavior.

Possibilities for the Biological Control of Mycotoxins in Food and Feed

Seeking useful biological agents for mycotoxin detoxification has achieved success in the last twenty years thanks to the participation of many multidisciplinary teams. We have recently witnessed discoveries in the fields of bacterial genetics (inclusive of next-generation sequencing), protein encoding, and bioinformatics that have helped to shape the latest perception of how microorganisms/mycotoxins/environmental factors intertwine and interact, so the road is opened for new breakthroughs. Analysis of literature data related to the biological control of mycotoxins indicates the ability of yeast, bacteria, fungi and enzymes to degrade or adsorb mycotoxins, which increases the safety and quality of susceptible crops, animal feed and, ultimately, food of animal origin (milk, meat and eggs) by preventing the presence of residues. Microbial detoxification (transformation and adsorption) is becoming a trustworthy strategy that leaves no or less toxic compounds and contributes to food security. This review summarizes the data and highlights the importance and prospects of these methods.