Supramolecular Host-Guest Interaction-Driven Electrochemical Recognition for Pyrophosphate and Alkaline Phosphatase...

We report an electrochemical biosensor based on the supramolecular host-guest recognition between cucurbit[7]uril (CB[7]) and L-phenylalanine-Cu(II) complex for pyrophosphate (PPi) and alkaline phosphatase (ALP) analysis. First, L-Phe-Cu(II) complex is simply synthesized by the complexation of Cu(II) (metal node) with L-Phe (bioorganic ligand), which can be immobilized onto CB[7] modified electrode via host-guest interaction of CB[7] and L-Phe. In this process, the signal of the complex-triggered electro-catalytic reduction of H₂ O₂ can be captured. Next, due to the strong chelation between PPi and Cu(II), a biosensing system of the model "PPi and Cu(II) premixing, then adding L-Phe" was designed and the platform was applied to PPi analysis by hampering the formation of L-Phe-Cu(II) complex. Along with ALP introduction, PPi can be hydrolyzed to orthophosphate (Pi), where abundant Cu(II) ions are released to form L-Phe-Cu(II) complex, which gives rise to the catalytic reaction of complex to H₂ O₂ reduction. The quantitative analysis of H₂ O₂ , PPi and ALP activity was achieved successfully and the detection of limits are 0.067 μM, 0.42 μM and 0.09 mU/mL (S/N=3), respectively. With its high sensitivity and selectivity, cost-effectiveness, and simplicity, our analytical system has great potential to for use in diagnosis and treatment of ALP-related diseases.