Direct electrochemistry and electrocatalysis of hemoglobin on chitosan-room temperature ionic liquid-TiO2-graphene nanocomposite film modified electrode

TiO 2 -graphene nanocomposite was prepared by hydrolysis of titanium isopropoxide in colloidal suspension of graphene oxide and in situ hydrothermal treatment . The direct electrochemistry and electrocatalysis of hemoglobin in room temperature ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate, chitosan and TiO 2 -graphene nanocomposite modified glassy carbon electrode were investigated. The biosensor was examined by using UV-vis spectroscopy, scanning electron microscopy and electrochemical methods. The results indicated that hemoglobin remained its bioactivity on the modified electrode , showing a couple of well-defined and quasi-reversible redox peaks, corresponding to hemoglobin Fe III /Fe II couple. The kinetic parameters for the electrode reaction , such as the formal potential ( E o' ), the electron transfer rate constant ( k s ), the apparent coverage ( Γ ), and Michaelis–Menten constant ( K m ) were evaluated. The biosensor showed good electrochemical responses to the reduction of H 2 O 2 in the ranges of 1–1170   μM. The detection limit was 0.3   μM (S/N   =   3). The properties of this composite film, together with the bioelectrochemical catalytic activity , could make them useful in the development of bioelectronic devices, and investigation of electrochemistry of other heme proteins at functional interface.