Real-time determination of carcinoembryonic antigen by using a contactless electrochemical immunosensor

Abstract

A sensitive label-free and contactless impedance immunosensor is developed for the real-time interaction investigation between a cancer biomarker carcinoembryonic antigen (CEA) and its antibody CEA 5909. The immunosensor consists of one interdigitated electrode (IDE) based contactless microfluidic chip and a supplementary inductor. The thin insulation layer between the IDEs and the resolved solution makes the detection contactless, preventing electrode erosion, electrolysis, and bubble formation problems. The insulated IDEs are covered by a PDMS layer with a microchamber of 5 μL. The leakage capacitance of the microfluidic chip is compensated by the addition of a series inductor. Under resonant characterization conditions, reproducible determination of ionic solutions in phosphate-buffered saline (PBS) has been demonstrated, with a detection limit of 10 μM. The immunoreactions between antibody CEA 5909 and CEA, a cytokeratin 19 fragment (CYFRA21-1) and bovine serum albumin (BSA) were investigated under label and label-free conditions. The immunosensor is proved to have a specific binding process between CEA and antibody CEA 5909 with a detection limit as low as 100 fg mL⁻¹ in PBS within a few minutes.