An Electrochemical Biosensor for the Detection of EpCAM-Based Circulating Tumor Cells

Abstract

Cancer is the second leading cause of death globally, accounting for an estimated 10 million deaths per year. Most deaths occur during metastasis stages when cancer cells are shed from the solid tumor and spread to other parts of the cancer patient’s body (circulating tumor cell). An electrochemical immunosensor is a powerful analytical tool based on the specific interaction between antibody and antigen, in which the specific interaction is measured through electrical signals. This study aimed to develop an electrochemical immunosensor for circulating tumor cell detection using a screen-printed gold electrode (SPAuE). The developed immunosensor was fabricated by electropolymerized polyaniline (PANI) on the working electrode. Gold nanoparticles were then electrodeposited on PANI-modified SPAuE. Streptavidin molecules were immobilized on the PANI-modified SPAuE, followed by biotin-EpCAM antibody binding on the surface. Electrochemical measurements were performed using electrochemical impedance spectroscopy. The results showed an increase in charge transfer resistance related to an increase in MCF-7 cell concentrations in the range of 10 to 106 cells mL¬1 (relative correlation coefficient = 0.997) with a detection limit (LOD) as low as 2 cells mL ¬-1 (3Sa/b). The developed immunosensor also exhibited high selectivity and good reproducibility. The immunosensor could provide high-potential tools with sensitivity and selectivity to screen breast cancer cells in the early stage for point-of-care testing development.