Direct electrochemistry of hemoglobin on vertically aligned carbon hybrid TiO2 nanotubes and its highly sensitive biosensor performance

The present work is focused on developing a novel biomaterial platform to achieve enhanced direct electron transfer (DET) of hemoprotein and higher biosensor performance on vertically aligned carbon hybrid TiO2 nanotubes (C-TiO2 NTs). Using a simple surfactant-assisted method, controllable hybridization of TiO2 NTs with conductive amorphous carbon species is realized. The obtained C-TiO2 NTs is ingeniously chosen to serve as an ideal "vessel" for protein immobilization and biosensor applications. Results show that the appropriate hybridization of C into TiO2 NTs leads to a much better conductivity of TiO2 NTs without destroying their preponderant tubular structures or damaging their excellent biocompatibility and hydrophilicity. When used in loading proteins, the C-TiO2 NTs can be used as a super vessel for rapid and substantive immobilization of hemoglobin (Hb), with a large surface electroactive Hb coverage I* of 3.3×10(-)9 mol·cm(2). Enhanced DET of Hb is commendably observed on the constructed Hb/C-TiO2 NTs biosensor with a couple of well-defined redox peaks in a fast electron transfer process. The biosensor further exhibits fast response, high sensitivity and stability for the amperometric biosensing of H2O2 with the detection limit as low as 3.1×10(-8) mol/L.