Direct electron transfer of hemoglobin in a biocompatible electrochemical system based on zirconium dioxide nanotubes and ionic liquid

Highly-ordered zirconium dioxide (ZrO2) nanotubes were prepared with porous anodic alumina as the template by the liquid phase deposition technique. The obtained ZrO2 nanotubes were characterized by transmission electron micrograph (TEM) and X-ray diffraction (XRD). A new biocompatible nano-platform for the immobilization of hemoglobin (Hb) was developed by coating a chitosan (CHI) solution, in which the ZrO2 nanotubes, 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid ([BMIM]BF4) and Hb were dispersed, onto a glassy carbon electrode surface. Direct electrochemistry of the immobilized Hb on the electrode surface was then investigated. The results indicated that remarkable improvements on the direct electrochemistry of Hb were achieved. In addition, the potential application of the Hb immobilized electrode (Hb/ZrO2/[BMIM]BF4/CHI/GCE) in biosensing was demonstrated by the catalytic electrochemical reduction of nitrite ion (NO2−) in an aqueous solution.

► Highly-ordered ZrO2 nanotubes were prepared by liquid phase deposition technique.
► A Hb/ZrO2/[BMIM]BF4/CHI composite film modified electrode was fabricated.
► Well direct electron transfer of Hb on the composite film electrode was achieved.
► The composite film electrode shows good electrocatalytic responses to nitrite ion.