A label-free fluorescence strategy for sensitive detection of ATP based on the ligation-triggered super-sandwich

In this study, a label-free fluorescence strategy for sensitive detection of ATP based on the ligation-triggered super-sandwich is reported. We designed a double-stranded DNA (ds-DNA) probe as the substrate of ATP-dependent ligation. SYBR Green I (SG I), a double-duplex DNA specific dye, was employed as the readout signal. In the absence of ATP, the ligation would not occur and the ds-DNA remained intact. Further, a weak fluorescence could be observed due to the intercalation of SG I into the grooves of the ds-DNA probe. In the presence of ATP, T4 DNA ligase would catalyse the ligation between 3'-OH and 5'-PO4 ends between ds-DNA probes. As a result, more binding sites of the SG I were generated and a fluorescence enhancement was obtained. This method showed a good sensitivity with a detection limit of 200 pM and could perfectly discriminate ATP from its analogs.