Measurements
The measurements were done at steady-state conditions. There is an interval surface between bioactive layer and electrode surface. Sensor responses were defined as the difference between first and second steady-state signals obtained before and after substrate addition and registered at current density (μA/cm2). The changes in signals due to the substrate addition were recorded at 60th seconds. After each measurement, the electrodes were washed with distilled water and kept inworking buffer solution for 2 min. The decrease of the reduction current of molecular oxygen by the addition of maltose through the subsequent enzymatic reaction was used to determine the
maltose concentration. As given below; initially AG hydrolyses maltose to 2 mol D-glucose. Then PyOx catalyzes the regioselective C-2 oxidation of D-glucose to 2-keto-D-glucose, concomitant with the reduction of O2 to H2O2. Calculations weremade by using standard curves between the current signals of consumed oxygen and maltose concentration.