Electropolymerization of pyrrole-2-carboxylic acid and 4,4′-dihydroxybenzophenone on platinum electrodes.: Applications to assemble novel glucose sensors

The electropolymerization of pyrrole-2-carboxylic acid (PY-2-COOH) and of 4,4'-dihydroxybenzophenone (DHB) has been carried out on Pt electrodes by scanning the potential from +0.4 V to +1.4 V (vs. SCE) for PY-2-COOH and from 0.0 V to +0.8 V (vs. SCE) for DHB, at scan rate of 2-5 mV/s, in phosphate buffer (PBS) pH 8. To test the permselectivity of these polymers, cyclic voltammograms of H2O2, ascorbic acid (AA), uric acid (UA) and acetaminophen (APAP) were carried out and results were compared with those obtained at the bare electrode. The electropolymerization in the presence of glucose oxidase was also carried out. The probes were then tested as glucose sensors. Glucose was detected, by amperometric measurements at +0.6 V (vs. SCE). The linear response to glucose was in the range 7 x 10(-6)-1.8 x 10(-3) mol/L, for the sensor prepared with PPY-2-COOH and 4 x 10(-6)-2 x 10(-3) mol/L, for the sensor prepared with PDHB. The detection limit was 5 x 10(-6) mol/L for PPY-2-COOH and 2 x 10(-6) mol/L for PDHB. The response time of both polymers was 3-5 s. The stability of the electropolymerized films and the glucose probes was evaluated, in storage and operational conditions The glucose probes, stored in buffer at 4 degrees C when not in use, showed a residual enzyme activity of 50%, after about two months.