Characteristics of a Miniature Compartment-less Glucose−O2 Biofuel Cell and Its Operation in a Living Plant

Abstract
We report the temperature, pH, glucose concentration, NaCl concentration, and operating atmosphere dependence of the power output of a compartment-less miniature glucose−O2 biofuel cell, comprised only of two bioelectrocatalyst-coated carbon fibers, each of 7 μm diameter and 2 cm length (Mano, N.; Mao, F.; Heller, A. J. Am. Chem. Soc.2002, 124, 12962). The bioelectrocatalyst of the anode consists of glucose oxidase from Aspergillus niger electrically “wired” by polymer I, having a redox potential of −0.19 V vs Ag/AgCl. That of the cathode consists of bilirubin oxidase from Trachyderma tsunodae “wired” by polymer II having a redox potential of +0.36 V vs Ag/AgCl (Mano, N.; Kim, H.-H.; Zhang, Y.; Heller, A. J. Am. Chem. Soc.2002, 124, 6480. Mano, N.; Kim, H.-H.; Heller, A. J. Phys. Chem. B2002, 106, 8842). Implantation of the fibers in the grape leads to an operating biofuel cell producing 2.4 μW at 0.52 V.