A direct electrochemical method to reduce graphene oxide nanoribbons was proposed. The reduced graphene nanoribbons (RGNRs) could be functionalized with water-soluble iron(III) meso-tetrakis(N-methylpyridinum-4-yl) porphyrin (FeTMPyP) via pi-pi noncovalent interaction on electrode surface. The resulting FeTMPyP/RGNRs film showed excellent electrocatalysis toward the reduction of dissolved oxygen at peak potential of -0.28 V. Using glucose oxidase as model enzyme, a biosensor based on the consumption of O(2) was developed for amperometric detection of glucose ranging from 0.5 mM to 10 mM. This biosensor could be successfully applied in the detection of glucose in human serum. The FeTMPyP functionalized RGNRs provided a platform for electrocatalysis and biosensing of oxidase substrates. (C) 2010 Elsevier B.V. All rights reserved.