Amperometric fructose sensor based on direct bioelectrocatalysis

Fructose dehydrogenase (EC 1.1.99.11) from bacterial membranes was immobilized on a carbon paste electrode by covering the enzyme layer with a dialysis membrane. The fructose dehydrogenase-modified carbon paste electrode showed a current response to d-fructose without the addition of any external electron transfer mediators. The current response was independent of the oxygen concentration in the solution. Steady-state currents were obtained when measured at fixed electrode potentials. The dependence of the steady-state current on the potential, the pH of the solution and the temperature was studied. On the basis of this investigation, it was shown that the fructose dehydrogenase-modified carbon paste electrode could be used as an unmediated amperometric fructose sensor. d-Fructose in fruits was measured using the present electrode. A method of eliminating the effect of l-ascorbic acid is also described.