Direct electron transfer of hemoglobin in layered α-zirconium phosphate with a high thermal stability

A heme protein hemoglobin (Hb) was reacted with preexfoliated layered α-zirconium phosphate (α-ZrP) platelets. An X-ray diffraction (XRD) pattern of small range showed that the exfoliated α-ZrP platelets reassembled after the addition of Hb molecules, with the protein intercalated between the layers. UV–Vis and Fourier transform infrared (FTIR) spectra analysis displayed that no significant denaturation occurred to the intercalated protein. The bioactivity of Hb was also investigated by testing the electrochemical properties of the Hb/α-ZrP composite. Results showed that the intercalation of Hb into the layered material not only improved the thermal stability of Hb but also enhanced the direct electron transfer ability between protein molecules and electrode. The protein still showed bioactivity after treatment at a temperature as high as 85 °C. A pair of well-defined redox peaks at approximately –0.37 and –0.32 V was observed on the cyclic voltammograms (CVs) of the Hb/α-ZrP composite modified electrode, and the electrode reactions showed a surface-controlled process with a single proton transfer. The resultant biosensor constructed by the Hb/α-ZrP composite displayed an excellent response to the reduction of hydrogen peroxide (H2O2) with good reproducibility.