▎ 摘　　要

Single stranded DNA (ssDNA)/graphene (GR) nanocomposites were prepared by a chemical route and cast on basal plane graphite (BPG) electrode to construct an ssDNA/GR modified electrode. Copperzinc superoxide dismutase (SOD) was adsorbed tightly on the surface of the modified electrode and the direct electron transfer of SOD was investigated using cyclic voltammetry. A couple of well-defined and quasi-reversible CV peaks of SOD can be observed and the separation of anodic and cathodic peak potentials is 90 mV in a phosphate buffer solution (pH 7.0). The electron transfer rate constant (ks) of SOD is 1.45 s(-1). Furthermore, this biosensor exhibits high analytical performance with a wide linear range (0.05-0.45 mu M), low detection limit (3 nM) and fast response time (1.5 s). The results demonstrate that the ssDNA-graphene nanocomposite offers a biocompatible material for the construction of biofuel cells, bioelectronics and biosensors.