Screening and identification of a DNA aptamer to concanavalin A and its application in food analysis.

Herein, a novel aptamer that targets concanavalin A (Con A), a plant lectin, is isolated using systematic evolution of ligands by an exponential enrichment (SELEX) technique. Nine rounds of SELEX screening over an agarose spin column have resulted in enrichment of eight sequences having high affinity to Con A. The highest affinity sequence was selected as a potent aptamer and characterized it in detail. The evolved Con A aptamer (Con A-aptabody) is a 41 nt ssDNA that binds the Con A specifically with a dissociation constant of 172.7 ± 29.7 nM. In silico analyses predict the Con A-aptabody to form G-quadruplex due to its G-rich sequence (GGAAGGCGGAGGG). A detection method developed using Con A-aptabody is found to have a detection range of 10-750 ng/mL with limits of detection and quantification being 13.22 and 44.09 ng/mL, respectively. The utility of the method is demonstrated by analyzing jack bean (Canavalia ensiformis), kidney bean (Phaseolus vulgaris), wheat (Triticum spp.), mung bean (Vigna radiata), and lentil (Lens culinaris) for their Con A contents. Hence, the developed Con A-aptabody provides a useful substitute to Con A-antibody for food analysis and related applications.