Amperometric d-Gluconate Sensor Using d-Gluconate Dehydrogenase from Bacterial Membranes

Abstract

d-Gluconate dehydrogenase (EC 1.1.99.3) from bacterial membranes was immobilized on the surface of a carbon paste electrode with mixed-in p-benzoquinone. The electrode surface was covered with a dialysis membrane. The current response to d-gluconate of electrodes with different amounts of the immobilized enzyme and different thicknesses of the dialysis membrane was studied, and their effects on the current response were quantitatively evaluated by the theory of biocatalyst electrodes with an entrapped mediator. On this basis, an electrode suited for a d-gluconate sensor was constructed and the current-response characteristics of the electrode (reponse time, linear range of the calibration curve, influences of pH, temperature, oxygen and so on) were investigated. The amperometric d-gluconate sensor required neither oxygen nor any reagents to be added to the test solution, and could measure d-gluconate in the range of 0.1 to 4 mm.