Fluorescent Turn-On Sensing of Zinc(II) and Alkaline Phosphatase Activity Using a Pyridoxal-5'-Phosphate Derived...

A novel Zn²⁺ ion and alkaline phosphatase (ALP) selective fluorescence turn-on sensor L was developed by reacting pyridoxal 5'-phosphate (PLP) with hydrazine. Sensor L shows significant flurescence enhancement at 476 nm due to the formation of a L-Zn²⁺ complex in 1:1 binding stoichiometry with the association constant of 3.1⋅10⁴ M^- 1. Using L, the concentration of Zn²⁺ can be detected down to 2.34 µM, and the practical utility of L was validated by quantifying Zn²⁺ in real water samples. Additionally, the receptor L was applied to mimic the dephosphorylation reaction catalysed by the enzyme ALP and the resulted fluorescence change was monitored to detect the ALP activity.