Hx. Ju et D. Leech, [OS(BPY)(2)(PVI)(10)CL]CL POLYMER-MODIFIED CARBON-FIBER ELECTRODES FOR THE ELECTROCATALYTIC OXIDATION OF NADH, Analytica chimica acta, 345(1-3), 1997, pp. 51-58
Carbon fiber microelectrodes modified with [Os(bpy)(2)(PVI)(10)Cl](+)
films are described, where bpy is 2,2'-bipyridine and PVI is a poly(vi
nylimidazole) polymer. The electrochemical properties of the polymer-m
odified microelectrodes were studied using cyclic voltammetry, chronoa
mperometry and normal pulse voltammetry. A charge transport diffusion
coefficient, D-ct, of (1.6+/-0.2)x10(-9) cm(2) s(-1) was estimated for
these films using chronoamperometry at a modified microdisk carbon fi
ber electrode. A heterogeneous electron transfer rate constant of (5.0
+/-0.5)x10(-4) cm s(-1) was evaluated by normal pulse voltammetry at t
he microcylinder electrode. The polymer-modified microelectrodes exhib
it electrocatalytic activity for the oxidation of NADH. An apparent Mi
chaelis-Menten constant of 0.23+/-0.02 mM for the catalytic oxidation
of NADH at the osmium-modified microcylinder electrode was evaluated a
nd compared to the value obtained at rotating-disk polymer-modified ma
croelectrodes. The advantages of the modified microelectrodes for moni
toring NADH levels are discussed.