Amperometric mediated carbon nanotube paste biosensor for fructose determination

A new mediated carbon nanotube paste (CNTP) amperometric biosensor for fructose is described. The biosensor is formed by a CNTP electrode modified with an electropolymerized film of 3,4-dihydroxybenzaldehyde (3,4-DHB) and is based on the activity of a commercial available D-fructose dehydrogenase (FDH) immobilized on an immobilon membrane placed on the top of the electrode surface. Analytical parameters such as enzyme immobilization, pH, temperature, and probe lifetime were studied and optimized. The biosensor response current was directly proportional to D-fructose concentration from 5 x 10(-6) to 2 x 10(-3) mol/L with a detection limit of 1 x 10(-6) mol/L and a good reproducibility (RSD = 1.8%, n = 5). The biosensor was used for the determination of fructose content in three honey samples and validated with a commercial spectrophotometric enzymatic kit.