In Vitro Selection and Characterization of an Aptamer for Detection of the Epitopic Peptide Sequence of the Thermostable Direct Hemolysin (TDH) Toxin of Vibrio parahemolyticus

Herein, we describe for the first time the selection of the single-stranded DNA aptamer that specifically binds to the thermostable direct hemolysin toxin of Vibrio parahemolyticus. The conventional SELEX procedure was followed for the selection of the aptamer, and the enriched sequence was obtained after nine iterative cycles. The selected aptamer, Ap3, was characterized by isothermal titration calorimetry (ITC) and an electrophoretic mobility shift assay (EMSA). EMSA confirms the affinity of the aptamer for the target peptide, and ITC reveals a significant Kd value of 6.6 mu M. The limit of detection of Ap3 was found to be 4.5 nM (r(2) = 0.955; y = 0.04x + 0.060). Our studies concluded that aptamer Ap3 binds to the toxin with a high affinity and specificity and has the potential to be used as a detecting probe in the development of a highly sensitive detection system for high-end seafood risk assessment and safety analysis.