Fe-substituted titanate nanosheets intercalated with hemoglobin for direct electrochemistry

Fe-substituted titania nanosheets (FTNS) are used as support matrixes for hemoglobin (Hb) immobilization and protein electrode fabrication to study the direct electron transfer between the redox centers of proteins and the electrode. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) reveal that the Hb-FTNS composite has an ordered layered structure with a monolayer arrangement in the interlayers. The native structure of the intercalated Hb is maintained, as indicated by the ultraviolet-visible (UV-vis) and Fourier-transform infrared (FTIR) spectroscopy. The Hb-FTNS modified electrode shows a fast direct electron transfer for the Hb Fe(III)/Fe(II) redox couple and exhibits good electrocatalytic properties for the reduction of H₂O₂. The sensitivity of Hb-FTNS modified electrode for the reduction of H₂O₂ is 156 mA M^-1 cm^-2 in the linear range of 2-65 μM, which is 18 times higher than that of Hb-titania nanosheets modified electrode (8.54 mA M^-1 cm^-2), suggesting that the Fe doping maybe an efficient method to improve the electrochemical performance of TNS for biosensors, biofuel cells and bioelectronics applications.