Modified DNA aptamers against sweet agent aspartame.

We obtained a modified DNA aptamer against sweetener, aspartame, by in vitro selection method. The modified DNA was prepared from dATP, dGTP, dCTP and a modified dTTP bearing a terminal amino group at C-5 position in place of thymidine by PCR using a hyper thermophilic DNA polymerase, KOD Dash DNA polymerase. The synthetic 102-mer DNA with a 60-mer random region was used as an initial template for the PCR. The PCR-amplified modified DNA library was applied to an aspartame-agarose column, and then the bound modified DNA was eluted from the column for the affinity chromatography selection. Repeating the procedure, we selected the modified DNA aptamer against aspartame.