▎ 摘　　要

Chitosan-dispersed graphene nano-flakes were prepared by a chemical route to reduce graphene oxide and dispersed fully in water to form a stable black aqueous solution. The as-prepared graphene nano-flakes were successfully immobilized on glassy carbon electrode to construct a graphene modified electrode. Cytochrome c was adsorbed tightly on the surface of the modified electrode and the direct electron transfer of Cytochrome c was achieved. Cytochrome c on the surface of electrode maintains its bioactivity and shows an enzyme-like activity for the reduction of nitric oxide, displaying a potential application for the fabrication of novel biosensors to sense nitric oxide. This research will enlarge the applications of graphene-based materials in biosensor field. (C) 2009 Elsevier B.V. All rights reserved.