Aptamer based turn-off fluorescent ATP assay using DNA concatamers

We describe a turn-off fluorescence-based strategy for the detection of ATP by making use of aptamer-triggered dsDNA concatamers. This sensitive and easily controlled method is based on consecutive hybridization induced by ATP aptamers and their sectional complementary DNAs to form dsDNA concatamers. The intercalator SYBR Green I (SGI) was employed as a fluorescent probe. In the absence of ATP, the probe produces a strong signal. However, on addition of ATP, the binding of aptamer and ATP cause the concatamers to collapse and to release SGI whose fluorescence then is quenched. The effect was exploited to design a selective ATP assay by relating the decrease in fluorescence to the ATP concentration. A lower detection limit of 6.1 μM and a linear response in the 0 to 5000 μM concentration range was accomplished. The strategy was applied to cellular ATP assays, and the results obtained by this strategy and by the gold standard method are in good agreement. The method is sensitive, simple and cost efficient, and hence is promising in terms of future applications to determine ATP in cellular and other systems. (author)