Development of a carbon nanotube paste electrode osmium polymer-mediated biosensor for determination of glucose in alcoholic beverages

This paper describes a new amperometric biosensor for glucose monitoring. The biosensor is based on the activity of glucose dehydrogenase (GDH) and diaphorase (DI) co-immobilized with NAD+ into a carbon nanotube paste (CNTP) electrode modified with an osmium functionalized polymer. This mediator was demonstrated to shuttle the electron transfer between the immobilized diaphorase and the CNTP electrode, thus, showing a good electrocatalytic activity towards NADH oxidation at potentials around +0.2 V versus Ag|AgCl, where interfering reactions are less prone to occur.The biosensor exhibits a detection limit of 10 μmol L−1, linearity up to 8 × 10−4 mol L−1, a sensitivity of 13.4 μA cm−2 mmol−1 L−1, a good reproducibility (R.S.D. 2.1%, n = 6) and a stability of about 1 week when stored dry at 4 °C.Finally, the proposed biosensor was applied for the determination of glucose in different samples of sweet wine and validated with a commercial spectrophotometric enzymatic kit.