▎ 摘　　要

A nitrite (NO2-) sensor has been fabricated by immobilizing cytochrome c (Cyt c) on a graphene/gold nanoparticle-chitosan (Gra/Au NPs-Chit) modified glass carbon electrode (GCE). Graphene/gold nanoparticles (Gra/Au NPs) nanocomposite was prepared by dispersing graphene in an aqueous solution of beta-cyclodextrin (beta-CD) and hydrogen tetrachloroaurate and followed by NaBH4 reduction. An aliquot of Gra/Au NPs in a 0.50 wt% chitosan solution was drop-coated on the surface of a GCE to form a Gra/Au NPs-Chit/GCE which was subsequently adsorbed with Cyt c. The Cyt c-Gra/Au NPs-Chit/GCE shows a quasi-reversible cyclic voltammetric redox couple at a formal potential of -0.037 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffer solution, suggesting that Gra/Au NPs-Chit film offers a biocompatible microenvironment for the Cyt c. It was found that the Cyt c-Gra/Au NPs-Chit sensor displays good electrocatalytic activity for NO2- oxidation at a relatively low working potential. The sensor possesses a linear response range of 10.0-420.0 mu M NO2- with a correlation coefficient of 0.9989 and a sensitivity of 110.0 mu A mM(-1). The limit of detection is determined as 2.46 mu M NO2- based on a signal-to-noise ratio of 3. The proposed sensor has been applied successfully to the determination of NO2- in spiked and real water samples.