An amperometric immunosensor based on an electrochemically pretreated carbon-paraffin electrode for complement III (C3) assay

An electrochemical immunosensor based on the adsorption of anti-complement III antibody onto an electrochemical pretreated carbon-paraffin electrode has been proposed for the detection of complement III (C-3). The competitive immunoassay format was adopted with horseradish peroxide-C-3 (HRP-C-3) as a tracer, 3,3'5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide as the enzyme substrates. In order to measure the amount of HRP-C3 binding onto the electrode surface, the product of the enzyme catalytic reaction was detected at 100 mV (vs. Ag/AgCl reference electrode). The system was optimized to realize a reliable determination Of C-3 in the range of 0.06-10 mug/ml. It exhibits some advantages, such as simplicity of fabrication, rapidity of measurement, and satisfactory sensitivity and reproducibility. (C) 2003 Elsevier Science B.V. All rights reserved.