Direct electrochemistry and electrocatalysis of hemoglobin based on poly(diallyldimethylammonium chloride) functionalized graphene sheets/room temperature ionic liquid composite film

The functionalized graphene nanosheets (PDDA-G) with poly(diallyldimethylammonium chloride) (PDDA) were synthesized and used to combine with room temperature ionic liquid (RTIL). The resulting RTIL/PDDA-G composite displayed an enhanced capability for the immobilization of hemoglobin to realize its direct electrochemistry. Moreover, the RTIL/PDDA-G based biosensor exhibited excellent electrocatalytic activity for the detection of nitrate with a wide linear range from 0.2 to 32.6 μM and a low detection limit of 0.04 μM at 3σ. This work opens a new way to functionalized graphene nanosheets with good biocompatibility and solubility in biosensors.