A charge-labeled electrochemical immunosensor: enhanced sensitivity by electrostatic interaction of the electrode/solution interface

The purpose of the research was to develop a proof-of-concept charge-labeled electrochemical immunosensor utilizing the electrostatic interaction of electrode surface. Gold nanorods, assembled with sulfonyl-terminated and carboxyl-terminated thiolated reagents, were applied as nanocarriers for negative charge and secondary antibodies due to their excellent biocompatibility and special interaction with mercapto groups. The sandwich-type immunosensor displayed excellent analytical performance including the broad linear concentration range of 1.0 fg mL(-)to 100 ng mL(-1) and a low detection limit of 1 fg mL(-1) for the detection of carcinoembryonic antigen. It was demonstrated that the electrostatic interaction contributed to the sensitivity of the immunosensor. Therefore, a proof-of-concept charge-labeled electrochemical immunosensor was proposed.