Amperometric glucose biosensors based on composite polymeric structures toprevent interferences

High sensitive glucose biosensors were realised by oxidative polymerisation of amphiphilic pyrrole monomer-glucose oxidase mixtures, previously adsorb ed on platinum electrodes. These sensors, based on H2O2 electrooxidation at 0.5V vs SCE, exhibited marked interferences due to electrooxildisable endo genous (ascorbate and urate) and exogenous (paracetamol) compounds. Bilayer structures, combining the preceding polymer film as an outer layer and ele ctrogenerated poly(phenylene diamine), overoxidised polypyrrolic films or N afion as the inner layer, were fabricated in order to minimise interference s. Finally, the use of Nafion as a semipermeable barrier appeared to be mor e efficient than the electrogenerated films. The Nafion-based biosensor exh ibited glucose sensitivity of 0.4 mA.M-1.cm(-2), while interference of asco rbate, urate and paracetamol was negligible.