Direct electrochemistry of hemoglobin based on nano-composite film of gold nanopaticles and poly (diallyldimethylammonium chloride) functionalized graphene

[Display omitted] ► AuNPs/PPDA-G multi-material has been fabricated which has high biocompatibility. ► AuNPs/PPDA-G multi-nanomaterials exhibited enhanced capability for hemoglobin immobilization. ► The larger surface concentration ( Γ*) of electroactive Hb was 3.85 × 10 −9 mol/cm 2. ► The biosensor showed prominent electrocatalytic activity for H 2O 2. ► The lower apparent Michaelis–Menten constant ( K m) was 0.51 mM, shown hemoglobin retaining its high bioactivity for H 2O 2 oxidation. The poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene nanosheets (PDDA-G) were prepared and gold nano-particles (AuNPs) were assembled on the surface of PDDA-G film through electrostatic interaction to construct the biocompatible interface. The resulting AuNPs/PDDA-G nanocomposite film exhibited enhanced capability for hemoglobin (Hb) immobilization and realized its direct electrochemistry. The surface concentration ( Γ*) of electroactive Hb on the surface of GCE was calculated to be 3.85 × 10 −9 mol/cm 2. Moreover, the AuNPs/PDDA-G based sensor showed prominent electrocatalytic activity for the detection of H 2O 2 with a wide linear range from 6 μM to 1010 μM and a low detection limit of 0.39 μM at 3 σ. Meanwhile, the apparent Michaelis–Menten constant ( K m) was 0.51 mM. This biosensor exhibited high sensitivity and fast responses, which may provide a novel way for fabrication of other graphene based sensors and broaden the application of graphene in biosensing.