DNA template triggered copper nanoparticles generation coupled with hybridization chain reaction amplification for simultaneous detection of three mycotoxins in food samples

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The co-occurrence of various mycotoxins in food, resulting from fungal infections, can lead to increased toxicity and enhanced harm through synergistic effects. In this work, a fluorescent assay was developed for simultaneous detection of zearalenone (ZEN), ochratoxin A (OTA) and aflatoxin B1 (AFB1) to address the issue of multiple mycotoxins co-contamination. Specific DNA hairpin-based aptamers were employed to recognize the mycotoxins and form a double-stranded DNA structure. Exonuclease III was introduced for the DNA cleavage, releasing single-stranded DNA triggers that could activate the assembling of DNA quadrilateral template. Copper nanoparticles were generated on the frame of DNA quadruplex template and produced fluorescent detection signals, while two hybridization chain reactions occurring on the different branches of the template and provided two additional detection signals. Inadequately reacted DNA chains were efficiently adsorbed and eliminated by Fe3O4@graphene oxide through magnetic separation. The limits of detection and linear ranges for ZEN, AFB1 and OTA were determined as 0.008 ng/mL, 0.003 ng/mL, 0.006 ng/mL and 0.010–100.000 ng/mL, 0.010–100.000 ng/mL, 0.010–50.000 ng/mL, respectively. Moreover, successful verification for real samples yielded recoveries from 99.2% to 102.7%, with a relative standard deviation of <5.23%. Artificially prepared toxic fungus infected samples were also analyzed. This method has demonstrated practical implications for the monitoring of food contaminants.