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 ( Γ ??) 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.