Fabrication of a third-generation glucose biosensor using graphene-polyethyleneimine-gold nanoparticles hybrid

The present study reports a novel approach for the fabrication of a third generation glucose biosensor based on the immobilization of glucose oxidase (GOx) on graphene-polyethyleneimine-gold nanoparticles hybrid (GNS-PEI-AuNPs) using glutaraldehyde as cross-linking reagent. A pair of well-defined redox peaks with the formal potential and peak separation value of -0.38 V and 60 mV was observed for the immobilized GOx on a gold electrode modified with GNS-PEI-AuNPs hybrid. The heterogeneous electron transfer rate (k(s)) for the redox center of the immobilized GOx, flavin adenine dinucleotide (FAD), was found to be 5.4 s(-1). An increase for the anodic peak current and a decrease for the cathodic peak current were recorded for the immobilized GOx on the modified electrode in the presence of glucose and the absence of oxygen. The obtained results confirmed that the prepared modified electrode presented bioelectrocatalytic activity towards glucose through a direct electron transfer (DET) mechanism. The response of the fabricated glucose biosensor was linear towards glucose in the concentration range between 1 and 100 mu M with the sensitivity about 93 mu A mM(-1) cm(-2). The limit of detection (LOD) for glucose sensing was estimated to be 0.32 mu M (S/N = 3). (C) 2016 Elsevier B.V. All rights reserved.