Novel amperometric immunosensor for rapid separation-free immunoassay of carcinoembryonic antigen.
A very sensitive immunosensor based on polyaniline/ Nafion/protein A (PA/NF/PrA) composite electrodes has been developed for the amperometric immunoanalysis with urease-labeled immunoreagents. The use of urease conjugated goat anti-RIgG (GaRIgG-Ur) as the labeled antibody and urea as the substrate with an amperometric detection at -200 mV (vs Ag/AgCl) resulted in a dynamic range of 50-2000 ng mL-1 and a low detection limit of 10 ng/mL (64 pM) for the immunoanalysis of rabbit immunoglobulin G (RIgG). Because of the special affinity between protein A and RIgG, the PA/NF/PrA electrode can be regenerated repetitively by changing the pH of the buffer solutions. Characteristics of the PA/NF/PrA/RIgG immunosensor and optimal conditions for the competitive immunoanalysis of RIgG with FIA were studied.