▎ 摘　　要

Inspired by the high electrocatalytic activity of electrochemically reduced graphene oxide-Au nanoparticles (ERGO-AuNPs) nanohybrid and their strong adsorption capacity for immobilizing biomolecules, we developed an ultrasensitive superoxide anion (O-2(center dot-)) electrochemical biosensor based on hemin immobilized on ERGO-AuNPs nanohybrid modified glass carbon electrode (GCE). The electrochemical properties of immobilized hemin were investigated. A considerably higher surface concentration (Gamma*) of the immobilized hemin was measured on the order of 1.02x 10(-7) mol cm(-2) . The results indicated that the ERGO-AuNPs nanohybrid enhanced the electrocatalytic activity of hemin for O-2(center dot-) detection due to the synergy generated by ERGO and AuNPs. The resulting biosensor exhibited an excellent amperometric response toward O-2(center dot-) , at linear ranges of 3.28 x10(-5) to 3.28 x 10(-4) M with sensitivities of 186 nA mu M-1 cm(-2) and 124 nA mu M-1 cm(-2) at 0.5 V and -0.1 V, separately. The apparent Michaelis-Menten constant (K-m ) was estimated to be 0.51 mM and 0.48 mM at 0.5 V and -0.1 V, respectively, which indicated a clearly stronger interaction of hemin with O-2(center dot-) . The results indicated that the biosensor have strong potential for analysis of biological molecules.