Terbium doping of graphitic carbon nitride endows a highly sensitive ratiometric fluorescence assay of alkaline phosphatase

Terbium doped graphitic carbon nitride (g-C 3 N 4 :Tb) gives rise to two exceptional emissions at λ ex / λ em = 290/490 nm and 290/546 nm, with extremely narrow peak widths of FWHM < 12 nm as well as a large Stokes shift of >200 nm. The modification of g-C 3 N 4 :Tb with HOOC-PEG-COOH provides a ratiometric fluorescent probe which ensures highly sensitive detection of alkaline phosphatase (ALP) activity based on the inner filter effect (IFE). Terbium doped g-C 3 N 4 produces two exceptional emissions with extremely narrow peaks with FWHM < 12 nm and a large Stokes shift of >200 nm. Its modification with HOOC-PEG-COOH endows a ratiometric fluorescence sensitive assay of alkaline phosphatase.