Gold Nanoparticle-labeled Electrochemical Immunoassay Using Open Circuit Potential for Human Chorionic Gonadotropin Detection

This study presents a new approach for an electrochemical immunoassay using gold nanoparticle (AuNP)-labeled antibodies and pre-oxidation and reduction processes, followed by open circuit potential (OCP) measurement. Detection of the pregnancy marker, human chorionic gonadotropin hormone (hCG), was used as a model. After preparation of a sandwich-type immunosystem, the pre-oxidation and reduction processes were applied, followed by OCP detection. The applied potential and time period were studied for the optimization of pre-oxidation and reduction processes. We observed that the pre-oxidation potential of 1.2V for 60s and reduction potential of -0.2V for 30s provided the highest OCP signal. The detection limit was 79pg/mL using the optimal conditions. This system could be applied to a simplified and miniaturized diagnostic system for integration in compact analytical devices.