Graphene bridged enzyme electrodes for glucose biosensing application

The fabrication of glucose oxidase (GOx) enzyme electrodes with controlled alternate enzyme and graphene layers is described. GOx was first modified with pyrene functionalities in order to be self-assembled onto a graphene basal plane via non-covalent π-π stacking interaction. Fluorescence spectroscopy analysis revealed that about 5.4 pyrene functional groups were attached to each GOx and the pyrene functionalized GOx retained more than 76% of the biocatalytical activity compared with the native enzyme. Via alternate layer-by-layer self-assembly of graphene and pyrene functionalized GOx, mono- and multi-layered enzyme electrodes with controlled biocatalytical activity can be easily fabricated. The biocatalytical activity of the as-prepared enzyme electrodes increased with increasing graphene and GOx layers and increased insignificantly when the layers reached four. Such multi-layered enzyme electrodes with controlled nanostructure exhibited reliable application in human serum samples analysis with high detection sensitivity, good stability and repeatability. A broad linear detection limit of 0.2 to 40 mM was obtained.