A ratiometric fluorescence strategy based on dual-signal response of carbon dots and o-phenylenediamine for ATP detection

Herein, a convenient method is developed for ratiometric fluorescence detection of ATP (adenosine triphosphate) based on CDs-OPD (carbon dots- o-phenylenediamine). In the absence of ATP, oxOPD, the colored oxidation product of OPD fabricated by a redox reaction occurred between OPD and Cu2+, not only quenches the fluorescence of CDs, but also emits a yellow fluorescence which acts as another signal element. However, ATP will compete with OPD to chelate Cu2+ inhibiting the redox reaction, which hampers the formation of oxOPD resulting in the diminution of IFE (inner filter effect) between CDs and oxOPD, then the fluorescence of CDs restores. ATP-induced dual-signal response of the CDs-OPD/Cu2+ system makes ratiometric assay possible. The method exhibits high sensitivity toward ATP with a detection limit of 0.43 μmol L−1. Furthermore, the semi-quantitative measurement of ATP is available by naked eyes through the color of fluorescence and solution. Finally, the developed method is employed for the quantification of ATP in practical samples with satisfactory results.