Cationic conjugated polyelectrolyte-based sensitive fluorescence assay for adenosinetriphosphate and alkaline phosphatase

The cationic water-soluble poly(diethynylfluorene-co-diethynylcarbazole-co-diethynylbenzothiadiazole) (P1–P3) were synthesized and used for adenosine triphosphate (ATP) detection. The incorporation of diethynylbenzothiadiazole (DBT) into the polymer backbone offers dual emissive polyelectrolytes with both blue and red emission bands in the dilute solution resulting from incomplete intramolecular energy transfer. In the solution of P2, addition of ATP can quench the emission of fluorene-co-carbazole units of P2 more efficiently than that of DBT segments, which causes the fluorescent color change from blue to red. The asymmetric quenching of the blue and red emission bands in the presence of ATP might become a possible method for a real-time ATP detection. In addition, when ATP is cleaved into fragments by enzyme alkaline phosphatase (ALP), the blue emission of P2 can be recovered. Thus, it is possible to assay the enzyme activity by triggering the change in color and intensity of the emission of the solution of P2.