A sensitive colorimetric and fluorescent sensor based on imidazolium-functionalized squaraines for the detection of GTP and alkaline phosphatase in aqueous solution.

Imidazolium-functionalized squaraine ImSQ8 is synthesized as a sensitive colorimetric and fluorescent chemosensor for GTP in aqueous solution. The detection limit of GTP reaches 5.4 ppb. Its applications in the live-cell imaging and enzyme activity assay have also been demonstrated.