Development and performance assessment of a multi-walled carbon nanotube/iron oxide nanocomposite-based electrochemical immunosensor for precise and ultrasensitive detection of carcinoembryonic antigen

An electrochemical immunosensor was designed and fabricated for the purpose of sensing the carcinoembryonic antigen (CEA) biomarker. The immunosensor utilized a novel approach for surface modification with a composite comprising Fe 3 O 4 nanoparticles decorated on carboxyl functionalized multi-walled carbon nanotubes (COOH-MWCNTs). This distinctive surface tailoring of the glassy carbon electrode (GCE), amplified signals and facilitated electron transfer. The MWCNTs with COOH groups served as an excellent substrate for electrode modification, enabling the formation of a sandwich-like structure by binding to anti-CEA antibody. Additionally, Fe 3 O 4 nanoparticles played a crucial role in electron transfer facilitation. The presence of HRP conjugated with the anti-CEA antibody triggered the reduction of H 2 O 2 in the electrochemical system of the sensor, resulting in an augmentated current. The concentration of CEA was directly proportional to the immunosensor analytical performance. The immunosensor demonstrated a suitable linear range from 0.005 ng mL −1 to 2.5 ng mL −1 , with a limit of detection (LOD) of 0.3 pg mL −1 . Notably, this immunosensor demonstrated exceptional reproducibility and stability, showcasing its suitability for measuring CEA in both real serum samples. These promising outcomes establish an overview for the adoption of such sensors into diagnostic clinics in the future. Graphical abstract