Determination of T-2 Toxin and HT-2 Toxin in Milk: A Comparison of Three Formats of Immunoassays

Portable T-2 toxin biosensor based on target-responsive DNA hydrogel using water column height as readout

T-2 toxin, a hazardous mycotoxin often present in cereals and products based on cereals, poses a substantial risk to humans and animals due to its high toxicity. The development of uncomplicated, quick and highly sensitive methods for detecting T-2 toxin is imperative. In this work, a portable sensing system was constructed using water column height as a readout device in combination with a controlled release system, which allows for an accurate quantitative analysis of T-2 toxin without the need for expensive instrumentation or skilled technicians. Hyaluronic acid (HA) hydrogel was constructed by double cross-linked DNA/aptamer hybrids with polyethyleneimine (PEI) and embedded with platinum nanoparticles (Pt NPs). The aptamer specifically bound to T-2 toxin in its presence, resulting in the disruption of the hydrogel and subsequent release of the Pt NPs. These Pt NPs were later mixed with a solution of H2O2 in a confined reaction flask, leading to the decomposition of H2O2 into O2. A glass capillary tube containing a column of red water had been inserted into the cap of the reaction flask, and the low solubility of O2 led to an increase in pressure within the reaction unit, causing the red water column to rise. There is a good linear correlation between the height of the capillary liquid level and the T-2 toxin concentration in the range of 20 ng/mL to 6 μg/mL. The system has been successfully used to detect T-2 toxin in samples of barley tea and corn.

T-2 Toxin/HT-2 Toxin and Ochratoxin A ELISAs Development and In-House Validation in Food in Accordance with the Commission Regulation (EU) No 519/2014

T-2 toxin/HT-2 toxin (T-2/HT-2) and ochratoxin A (OTA) are mycotoxins that can contaminate a variety of agricultural commodities. To protect consumers' health, indicative limits for T-2/HT-2 and maximum limits for OTA have been set by the European Commission, requiring food business operators and controlling agencies to conduct routine checks for the presence of these harmful contaminants. Screening methods are increasingly used for monitoring purposes. Due to the demand for new and improved screening tools, two individual detection methods, T-2/HT-2 and OTA enzyme-linked immunosorbent assays (ELISAs), were developed in this study. The T-2/HT-2 ELISA was based on a T-2 monoclonal antibody with an IC50 (50% inhibitory concentration) of 0.28 ng/mL and 125% cross-reactivity with HT-2. As regards the OTA ELISA, a new sensitive monoclonal antibody specific to OTA with an IC50 of 0.13 ng/mL was produced. Both developed ELISA tests were then validated in agricultural commodities in accordance with the new performance criteria guidelines for the validation of screening methods for mycotoxins included in Commission Regulation (EU) No 519/2014. The T-2/HT-2 ELISA was demonstrated to be suitable for the detection of T-2/HT-2 in cereals and baby food at and above the screening target concentration (STC) of 12.5 μg/kg and 7.5 μg/kg, respectively. The OTA ELISA was shown to be applicable for the detection of OTA in cereals, coffee, cocoa and wine at and above the STC of 2 μg/kg, 2.5 μg/kg, 2.5 μg/kg and 0.4 ng/mL, respectively. The accuracy of both ELISAs was further confirmed by analysing proficiency test and reference samples. The developed methods can be used for sensitive and high-throughput screening for the presence of T-2/HT-2 and OTA in agricultural commodities.

Development of a Rainbow Lateral Flow Immunoassay for the Simultaneous Detection of Four Mycotoxins

A multiplex lateral flow immunoassay (LFIA) for the determination of the mycotoxins deoxynivalenol, zearalenone, and T2/HT2-toxin in barley was developed with luminescent quantum dots (QDs) as label. The synthesized QDs were hydrophilized by two strategies, that is, coating with an amphiphilic polymer or silica. The water-soluble QDs were compared with regard to their bioconjugation with monoclonal antibody (mAb) and were tested on a LFIA. Silica-coated QDs that contained epoxy groups were most promising. Therefore, green, orange, and red epoxy-functionalized silica-coated QDs were conjugated with anti-ZEN, anti-DON, and anti-T2 mAb, respectively. The LFIA was developed in accordance with the European Commission legal limits with cutoff limits of 1000, 80, and 80 μg/kg for deoxynivalenol, zearalenone, and T2/HT2-toxin, respectively. The LFIA gave a fast result (15 min) with a low false-negative rate (<5%), and the results were easy to interpret without any sophisticated equipment.

High-sensitivity chemiluminescent immunoassay investigation and application for the detection of T-2 toxin and major metabolite HT-2 toxin

BACKGROUND

T-2 toxin is a widely distributed mycotoxin in cereals. HT-2 toxin is the major metabolite, which is also a contaminant in cereals. T-2 toxin and HT-2 toxin have been identified as having carcinogenic, hepatotoxic, teratogenic and immunotoxic properties. To reduce the risk of contamination, a rapid, highly sensitive and inexpensive assay for the detection is required.

RESULTS

In this study a high-sensitivity chemiluminescent enzyme-linked immunoassay (CL-ELISA) of T-2 toxin and HT-2 toxin was developed. With the help of the chemiluminescent substrate, this protocol showed a highly sensitive character with an IC₅₀ as low as 33.28 ng mL^-1 and 27.27 ng mL^-1 for T-2 and HT-2, respectively. In addition, this method had no cross-reaction with other structurally related mycotoxins.

CONCLUSION

These results indicated that the developed CL-ELISA could be applied for the detection of T-2 toxin and HT-2 toxin in actual samples without complicated steps. © 2016 Society of Chemical Industry.