GLUCOSE ELECTRODES BASED ON CROSS-LINKED [OS(BPY)(2)](+ 2+) COMPLEXEDPOLY(L-VINYLIMIDAZOLE) FILMS/

Enzyme electrodes based on a redox hydrogel formed upon complexing wat er-soluble poly(1-vinylimidazole) (PVI) with [Os(bpy)(2)C1](+) and cro ss-linked with water-soluble poly(ethylene glycol) diglycidyl ether (m olecular weight 400, peg 400) are described. The properties of the ele ctrodes depended on their polymers' osmium content, the extent of cros s-linking, the pH, and the ionic strength in which they were used. The redox hydrogels' electron diffusion coefficients (D,) increased with osmium content of their polymers. The D-e values were 1.5 x 10(-8), 1. 3 x 10(-8), and 4.3 x 10(-9) cm(2)/s for PVI3-Os, PVI5-Os, and PVI10-O s, respectively, the subscripts indicating the number of monomer units per osmium redox center. D, decreased with increasing ionic strength and increased upon protonation of the polymer. In glucose electrodes, made by incorporating into their films glucose oxidase (GOX) through c ovalent bonding in the cross-linking step, glucose was electrooxidized at >150 mV (SCE). The characteristics of these electrodes depended on the GOX concentration, film thickness, O-2 concentration, pH, NaCl co ncentration, and electrode potential. The steady-state glucose electro oxidation currents were independent of the polymers' osmium content in the studied (3-10 monomer units per osmium center) range; Electrodes containing 39% GOX reached steady-state glucose electrooxidation curre nt densities of 400 mu A/cm(2) and, when made with: thick gel films, w ere selective for glucose in the presence of physiological concentrati ons of ascorbate and acetaminophen.