Ultrasensitive and rapid detection of T-2 toxin using a target-responsive DNA hydrogel

The T-2 toxin is generated as a secondary metabolite by various species of Fusarium that are found extensively in barley, wheat, maize, and oats; consequently, the development of methods that can rapidly and efficiently detect this toxin is vital. Herein, we report on a novel and highly sensitive method based on DNA hydrogels and etched gold nanorods (AuNRs) to detect the T-2 toxin. The T-2 toxin aptamer acts as a cross-linking agent for a hydrogel in which horseradish peroxidase (HRP) is uniformly embedded. The target T-2 toxin binds to the aptamer, causing the hydrogel to collapse and release the embedded HRP, which catalyzes the reaction of H 2 O 2 with KI to produce I 2 that etches the AuNRs. The UV spectrum of the AuNRs is blue-shifted following etching; this shift is proportional to the T-2-toxin content. This method offers a low limit of detection (0.87 pg mL −1 ), low limit of quantification (2.90 pg mL −1 ), and wide detection range (0.01–10000 ng mL −1 ). Moreover, coffee, corn, and soybean were assayed using the optimized method. The approach offers good recoveries and relative standard deviations of 93.72–103.07 % and 3.87–7.07 %, respectively. The total assay time was 1.5 h. Thus, the new method is promising as an ultrasensitive assay for detecting various small molecules in complex matrices.