ZnO-MWCNTs/Nafion inorganic–organic composite film: Preparation and application in bioelectrochemistry of hemoglobin

Multi-walled carbon nanotubes (MWCNTs) were coated with ZnO by a hydrothermal method. The resulting nanocomposites were mixed with the Nafion solution to form a composite matrix for the fabrication of hemoglobin (Hb) biosensor. To prevent the leak of Hb molecules of the biosensor, silica sol–gel film was coated on the surface of the Hb/ZnO-MWCNTs/Nafion electrode. The silica sol–gel/Hb/ZnO-MWCNTs/Nafion film exhibited a pair of well-defined, quasi-reversible redox peaks. This biosensor showed excellent electrocatalytic activity to H2O2. The sensitivity and apparent Michaelis–Menten constant of this Hb biosensor to H2O2 were 1.31 A/(M cm2) and 82.8 μmol/L, respectively, which indicated that Hb had high affinity to H2O2.