SiO2/C/Cu(II)phthalocyanine as a biomimetic catalyst for dopamine monooxygenase in the development of an amperometric sensor

A mesoporous carbon ceramic SiO2/50 wt% C (S-BET = 170 m(2) g(-1)), where C is graphite, was prepared by the sol-gel method. This material was used as matrix to support copper phthalocyanine (CuPc), prepared in situ on their surface, to assure homogeneous dispersion of the electrocatalyst complex in the pores of the matrix. Pressed disk electrodes made with SiO2/C/CuPc was tested as amperometric sensors for dopamine. Under optimized conditions, at -20 mV vs SCE in 0.08 mol dm(-3) Britton-Robinson buffer (BRB) solution (pH = 6.0) containing 100 mu mol dm(-3) of H2O2, a linear response range for dopamine from 10 up to 140 mu mol dm(-3) was obtained with a sensitivity of 0.63 (+/- 0.006) nA dm(3) mu mol(-1) cm(-2) and the limit of detection LOD was 0.6 mu mol dm(-3). The sensors presented stable response during successive determinations. The repeatability, evaluated in terms of relative standard deviation of 1.37% for n = 10 and 10 mu mol dm(-3) dopamine. The response time was 1 s and lifetime 9 months. Finally, the sensor was tested to determine dopamine in the sample, and gives very good results for its determination. The presence of other phenols like catechol and resorcinol did not show any interference in the detection of dopamine on this electrode, even in the same concentration with the dopamine. (C) 2011 Elsevier Ltd. All rights reserved.