A nanoporous zirconium phytate film for immobilization of redox protein and the direct electrochemical biosensor

Abstract

Due to the strong chelating ability between phosphates and metal ions, we synthesized a new porous nanomaterials – zirconium phytate by the method of direct precipitation. Then, the morphology of as-made zirconium phytate was characterized by TEM and FESEM. Further, we tried to employ the nanoporous film of zirconium phytate as a substrate for making the HRP based biosensor by drop-coating method and investigate the electrochemical behavior of enzyme. The UV–vis absorption spectroscopy and electrochemical results showed that the absorbed HRP retained its bioactivity and realized direct electron transfer due to the improved biocompatibility of zirconium phytate. Moreover, the biosensor displayed good bioelectrocatalytic ability toward the reduction of H 2O 2 with a linear response to H 2O 2 over a concentration range from 6.67 × 10 −7 to 6 × 10 −6 mol/L, and a detection limit of 5.3 × 10 −7 mol/L at a signal-to-noise ratio (S/N) = 3. The Michaelis–Menten constant K M app was estimated to be 0.306 mmol/L. The biosensor exhibited low detection limit, high enzymatic activity and good reproducibility and stability.