We report for the first time the use of quaternized chitosan (QCHI) for the immobilization of gold nanopartides (NP) and glucose oxidase (GOD), the characterization of the resulting platform and its biocatalytic activity using glucose as substrate. The chemical substitution of chitosan has allowed us to work at physiologic pH to build up self-assembled layers of QCHI-NP as platform for the enzyme immobilization. The adsorption of GOD was analyzed by surface plasmon resonance (SPR) to compare the surface coverage of GOD in absence and presence of the QCHI-NP platform. The results obtained with cyclic voltammetry and scanning electrochemical microscopy (SECM) revealed that the adsorption of NP improves the conductivity of the structure and its electrochemical reactivity, facilitating the oxidation of the hydrogen peroxide produced by GOD. The electrodes modified with NP present higher amperometric response demonstrating the efficient transduction of the enzymatic activity in this structure. (C) 2010 Elsevier Ltd. All rights reserved.