On the parameters affecting the characteristics of the “wired” glucose oxidase anode

We recently described a redox polymer with an Os ( N , N ′ - dialkylated biimidazole ) 3 2 + / 3 + redox center with a redox potential of −195 mV vs. Ag|AgCl, 800 mV reducing relative to its 2,2′-bipyridine analog. The tethering of the centers to a poly(4-vinylpyridine) backbone through a 13 atom long spacer arm, provided for an apparent electron diffusion coefficient as large as 5 × 8.10−6 cm2 s−1. The glucose electro-oxidation catalyst formed by “wiring” glucose oxidase with this polymer allowed the electro-oxidation of glucose already at −360 mV vs. Ag|AgCl at pH 7.2, near the reversible potential of glucose oxidase, at a current density of 1.3 mA cm−2 in the presence of 32 mM glucose concentration. Here we consider the parameters affecting the characteristics of this anode, compare the characteristics with those of an anode made with a short-tethered “wire” and describe the optimization of the composition of the “wired” glucose oxidase.