Liquid phase deposition of hemoglobin/SDS/TiO2 hybrid film preserving photoelectrochemical activity

This work demonstrates that liquid phase deposition (LPD) technique provides a novel approach to the immobilization of hemoglobin (Hb) in TiO2 film for studying the direct electron transfer of Hb. Using the LPD process, a hybrid film composed of Hb, TiO2 and sodium dodecylsulfonate (SDS) is successfully prepared on the electrode surface. The surface morphology of as-deposited Hb/SDS/TiO2 film shows a flower-like structure. The cyclic voltammetric measurement indicates that the LPD hybrid film facilitates the electron transfer of Hb, which yields a pair of redox peaks prior to the characteristic voltammetric peaks of TiO2. Due to the electrocatalytic activity of Hb towards H2O2, the Hb/SDS/TiO2 hybrid LPD film can be utilized as an H2O2 sensor, showing a sensitive response linearly proportional to the concentration of H2O2 in the range of 5.0 × 10− 7–4.0 × 10− 5 mol/L. At the same time, the Hb/SDS/TiO2 hybrid film preserves the photoelectrochemical activity of TiO2. The photovoltaic effect on the electrochemical behavior of Hb/SDS/TiO2 film is observed after long-time UV irradiation on the film, which could improve the calibration sensitivity for H2O2.

Research highlights
► Hb/SDS/TiO2 hybrid film is prepared on electrode surface by LPD technique.
► Electron transfer between Hb and electrode is facilitated in the hybrid LPD film.
► The LPD Hb/SDS/TiO2 film preserves the photoelectrochemical activity of TiO2.
► The sensitivity for H2O2 is improved based on the photovoltaic effect of TiO2.