Mechanical and electrochemical characteristics of composites of wired glucose oxidase and hydrophilic graphite

In glucose electro-oxidation catalyzing redox hydrogels, through which reac tion centers of glucose oxidase are electrically connected (wired) to elect rodes, electrons diffuse by their transfer between colliding redox centers. The colliding centers are tethered to the hydrated redox polymer. The mobi lity of the polymer segments and the diffusivity of electrons increase upon hydration and swelling, but the gels lose their strength and are readily s heared off when mechanically stressed. As a result, gels that are not highl y cross-linked are soft, but the upper kinetic limit of their glucose elect ro-oxidation current density is high, similar to 1.2 mA cm(-2). Gels that a re highly cross-linked are mechanically strong, but the upper kinetic limit of their current density is only similar to 0.4 mA cm(-2). We show here th at composites of >90 wt % hydrophylized graphite particles and <10 wt % hig hly cross-linked, glucose-oxidase containing redox hydrogels are mechanical ly strong, yet their kinetically limited current density is high, 1.6 mA cm -l (C) 2000 The Electrochemical Society. S0013-4651(00)03-007-X. All rights reserved.