A glucose biosensor based on electro-enzyme catalyzed oxidation of glucose using a HRP-GOD layered assembly

The assembly and the characterization (by DC cyclic voltammetry and flow injection analysis (FIA) mode) of a bienzymatic biosensor for glucose is described. The biosensor is constituted by a glucose oxidase (GOD)-entrapping cellulose triacetate membrane, layered onto a polymeric membrane (polystyrene cross-linked with 1% divinyl benzene functionalized with tributylmethyl phosphonium chloride (TBMPC)) embedding horseradish peroxidase (HRP), previously blocked onto a pyrolitic graphite electrode (PGE). Under flowing conditions, the biosensor, which gives place to direct, unmediated electron-transfer, responds linearly to the glucose up to 5.0 MM with a precison always better than 5%, and the detection limit was 0.07 mM. The influence of different experimental parameters, like temperature, flow rate, applied potential, interferents, etc., has been evaluated. For what concerns the potential interferences, no interfering species, as ascorbic acid, urea, etc., affects the biosensor response. The biosensor, characterized by an operational stability of at least twenty days, has been successfully tested on real samples.