Screening and Identification of DNA Aptamers against T-2 Toxin Assisted by Graphene Oxide

A high-affinity ssDNA aptamer that specifically binds to T-2 toxin was generated by the systemic evolution of ligands by exponential enrichment (SELEX) procedure assisted by graphene oxide (GO). After 10 rounds of selection against T-2 toxin, a highly enriched ssDNA pool was sequenced and the representative aptamers were subjected to binding assays to evaluate their affinity and specificity. Circular dichroism spectroscopy was also used to study the inherent interaction of T-2 toxin and the preferred aptamer Seq.16, which demonstrated a low dissociation constant (Kd) of 20.8 ± 3.1 nM and excellent selectivity for T-2 toxin. Using the selected aptamer Seq.16 as the recognition element, an aptamer-based fluorescent bioassay was developed for the measurement of T-2 in beer samples with a linear range from 0.5 to 37.5 μM (R(2) = 0.988) and a limit of detection (LOD) of 0.4 μM. The results indicate that GO-SELEX technology is appropriate for the screening of aptamers against small-molecule toxins, offering a promising application for aptamer-based biosensors.