An ultrasensitive electrochemical immunosensor for carcinoembryonic antigen detection based on staphylococcal protein A—Au nanoparticle modified gold electrode

The fabrication of staphylococcal protein A (SPA) film on Au nanoparticle (AuNPs)-modified electrode was done for the construction of electrochemical immunosensor. In this work, a highly sensitive electrochemical immunosensor for the detection of a tumor biomarker, carcinoembryonic antigen (CEA) was developed by absorption of anti-CEA antibodies on the SPA-AuNPs modified gold electrode. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques were employed in the determination of electrode responses and applicability. Under the optimized condition, the immunosensor displays a good linear response to CEA with a range from 1   pg/ml to 100   ng/ml and a detection limit of 0.1   pg/ml. Furthermore, samples of 1–50   ng/ml CEA in rat serum was detected using the immunosensor and the immunosensor showed acceptable recoveries when the CEA value is within the scope of clinical detection. It can be concluded that the immunosensor provides a promising ultrasensitive immunology strategy for clinical diagnosis.