A glucose biosensor has been developed by entrapment of glucose oxidas
e in a polythianaphthene film formed onto a platinum surface. Glucose
has been measured by H2O2 detection at +400 mV (vs. SCE). Electrochemi
cal kinetic constants for the enzyme electrode have been calculated an
d indicated that in the unsaturated region the rate limiting step is t
he diffusion of the substrate through the polymer. The biosensor exhib
ited a linear response in the range 0.05-7.4 mmol/L with a response ti
me of 30-60 s and a relative standard deviation of 5.4%. The presence
of the film onto the electrode prevents the oxidation of interfering a
gents such as ascorbic and uric acid. The use of additional polycarbon
ate membranes onto the electrode surface extended the linearity of the
response allowing the probe to be used in blood glucose analysis. The
amount of glucose in two control sera was measured using the biosenso
r. Results correlated well with the glucose nominal values.