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 H2O2 with KI to produce I2 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.