Development of an impedimetric immunobiosensor for measurement of carcinoembryonic antigen

This paper presents an impedimetric immunobiosensor for detecting the impedance signals of various concentrations of carcinoembryonic antigen (CEA), a type of protein molecule which is typically associated with certain tumors. The biosensor was developed by parallel electrodes and improved sandwich immunoassay, and used specific binding of antibodies to change the impedance signals of various CEA concentrations. We observed an obvious difference in impedance signals after 13 min, and a better linearity (a steep slope between impedance and CEA concentration) at 100 Hz. Finally, when the concentration of the AuNPs-anti-CEA antibody was diluted 30 for times, the detection limit for CEA concentration was 1 ng/mL with 1 μg/mL of anti-CEA antibody. Therefore, the developed biosensor has advantages including smaller sample volume (25 μL), rapid quantitative measurement (10 min), and smaller detectable concentrations (1 ng/mL).