Direct electrochemistry and electrocatalysis of hemoglobin immobilized in TiO2 nanotube films.

Titanium oxide nanotubes (TiO(2)-NTs) synthesized by the hydrothermal method had been prepared as the co-immobilization matrix to incorporate hemoglobin (Hb) successfully. The nanostructures of TiO(2)-NTs were investigated by X-ray diffraction and high-resolution electron microscopy. The Hb immobilized in TiO(2)-NTs had a similar structure to the native of Hb and retained its near-native conformations as characterized by the UV-vis and FT-IR spectroscopy. A couple of quasi-reversible redox peaks with a formal potential of -0.34 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffered saline (PBS) were observed. The amperometric response of the immobilized Hb linearly to H(2)O(2) concentration ranged from 4 microM to 64 microM with a detection limit of 4.637 x 10(-6)M and the high stability of the immobilized Hb in TiO(2)-NTs constituted a promising platform for the development of biosensors.