Utilizing the DNA Aptamer to Determine Lethal α-Amanitin in Mushroom Samples and Urine by Magnetic Bead-ELISA (MELISA)

Amanita poisoning is one of the most deadly types of mushroom poisoning. α-Amanitin is the main lethal toxin in amanita, and the human-lethal dose is about 0.1 mg/kg. Most of the commonly used detection techniques for α-amanitin require expensive instruments. In this study, the α-amanitin aptamer was selected as the research object, and the stem-loop structure of the original aptamer was not damaged by truncating the redundant bases, in order to improve the affinity and specificity of the aptamer. The specificity and affinity of the truncated aptamers were determined using isothermal titration calorimetry (ITC) and gold nanoparticles (AuNPs), and the affinity and specificity of the aptamers decreased after truncation. Therefore, the original aptamer was selected to establish a simple and specific magnetic bead-based enzyme linked immunoassay (MELISA) method for α-amanitin. The detection limit was 0.369 μg/mL, while, in mushroom it was 0.372 μg/mL and in urine 0.337 μg/mL. Recovery studies were performed by spiking urine and mushroom samples with α-amanitin, and these confirmed the desirable accuracy and practical applicability of our method. The α-amanitin and aptamer recognition sites and binding pockets were investigated in an in vitro molecular docking environment, and the main binding bases of both were T3, G4, C5, T6, T7, C67, and A68. This study truncated the α-amanitin aptamer and proposes a method of detecting α-amanitin.