In vitro selection of ssDNA aptamers that can specifically recognize and differentiate riboflavin and its derivative FAD

It is very meaningful and useful to select specific aptamers with capacity to distinguish small structural analogues, but it is difficult to carry out by traditional affinity chromatography-SELEX (systematic evolution of ligands by exponential enrichment) based on immobilized target molecules. In this paper, as a proof of concept, we selected DNA aptamers that can specifically recognize and differentiate riboflavin and its derivative flavin adenine dinucleotide (FAD) by a modified method. Here, the random DNA library was indirectly immobilized on streptavidin functional agarose beads by hybridization with its biotinylated short complementary strand, and the specific affinity between aptamers and its target would induce the aptamers to release from beads. Binding specificity can be tailored by performing an additional negative SELEX with the structure analogue of target. After about 10 rounds of selection, 6 aptamers for riboflavin and 2 aptamers for FAD with good affinities were isolated, and their dissociation constants (K(d)s) were all at low micromolar level. Moreover, as expected, most of these aptamers show high affinity and excellent selectivity for target molecules, almost no binding to structure analogues and purines, indicating this simple method could be used to select specific aptamers to distinguish small molecular targets with similar structures.