A novel hydrogen peroxide biosensor based on the immobilization of hemoglobin on three-dimensionally ordered macroporous (3DOM) gold-nanoparticle-doped titanium dioxide (GTD) film

The three-dimensionally ordered macroporous gold-nanoparticle-doped titanium dioxide (3DOM GTD) film was modified on the indium-tin oxide (ITO) electrode surface. Hemoglobin (Hb) has been successfully immobilized on the 3DOM GTD film and the fabrication process was characterized by Raman and UV–vis spectra. The results indicated that the Hb immobilized on the film retained its biological activity and the secondary structure of Hb was not destroyed. The direct electrochemistry and electrocatalysis of Hb immobilized on this film have been investigated. The Hb/3DOM GTD/ITO electrode exhibited two couples of redox peaks corresponding to the Hb intercalated in the mesopores and adsorbed on the external surface of the film with the formal potential of −0.20 and −0.48 V in 0.1 M PBS (pH7.0), respectively. The Hb/3DOM GTD/ITO electrode exhibits an excellent eletrocatalytic activity, a wide linear range for H2O2 from 5.0 μM to 1.0 mM with a limit of detection of 0.6 μM, high sensitivity (144.5 μA mM−1), good stability and reproducibility. Compared with the TiO2 nanoneedles modified electrode, the GTD modified electrode has higher sensitivity and response peak current. The 3DOM GTD provided a good matrix for bioactive molecules immobilization, suggesting it has the potential use in the fields of H2O2 biosensors.