A novel enzyme electrode system for glucose oxidation was constructed by co-immobilization of glucose dehydrogenase (GDH) and N,N'-diphenyl-pphenylenediamine (DPPD) on carbon electrodes. This enzyme electrode system was applied to porous carbon fabric to produce a glucose oxidation current of 7 mA/cm 2 , while the electrode catalytic activity was maintained at approximately 100% for more than 4 h, indicating that DPPD molecules were stably retained on the electrodes during the continuous redox cycling. Further, a stable mediation was also observed for other 4-aminodiphenylamine derivatives similar to DPPD.The difference was found in the adsorptivity between the reduced and oxidized forms of DPPD on the carbon electrode, suggesting that a portion of oxidized DPPD can access the active center of GDH without desorbing to solution. This electrode system with 4-aminodiphenylamine derivatives can be used in sensors for glucose monitoring and to anodes of separator-free glucose fuel cells.
K E Y W O R D S4-aminodiphenylamine derivatives, enzymatic fuel cells, enzyme electrode, glucose dehydrogenase, mediator Enzyme-modified electrodes are the core components of bioelectronic devices, such as biosensors, for medical analytes and biofuel cells. These types of electrodes can generate electricity from natural fuel molecules, such as glucose. [1][2][3][4][5][6][7][8][9][10][11] Most of these bioelectronic devices employ a mediated electron transfer between the enzyme active sites and electrode surface via a redox-active molecule called mediator. Conventional mediator molecules, such as ferricyanide, phenazine derivatives, and quinone derivatives, are soluble in water and freely diffuse into the active sites deep inside the protein shell of these enzymes. [9][10][11][12][13][14][15][16] However, enzymatic fuel cells with diffusing mediators require undesirable complex components (i.e., semiper-This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.