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

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 (Gamma*) of electroactive Hb on the surface of GCE was calculated to be 3.85 x 10(-9) mol/cm(2). Moreover, the AuNPs/PDDA-G based sensor showed prominent electrocatalytic activity for the detection of H2O2 with a wide linear range from 6 mu M to 1010 mu M and a low detection limit of 0.39 mu M at 3 sigma. 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. (C) 2011 Elsevier Ltd. All rights reserved.