Tj. Ohara et al., GLUCOSE ELECTRODES BASED ON CROSS-LINKED [OS(BPY)(2)](+ 2+) COMPLEXEDPOLY(L-VINYLIMIDAZOLE) FILMS/, Analytical chemistry, 65(23), 1993, pp. 3512-3517
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.