Impedometric Analysis and Characterization in the Development of an hCGÃ\x9f Biosensor

Detection and concentration monitoring of Human Chorionic Gonadotropin (hCG) and especially, its free beta-subunit, (hCG), is critical for various aspects of the human health. More importantly, they can be used as markers of gestational trophoblastic disease (GTD), germ cell tumors and some non-trophoblastic tumors. Detection of hCGbeta is also critical for patient treatment monitoring and for relapse detection. According to the literature, the use of hCGbeta as a tumor marker is limited by the lack of high sensitivity and specificity sensors. In this paper we present the first two steps of the development of an impedance biosensor, based on the formation of a stable antibody-antigen complex on gold microband electrodes and the preliminary results and analysis of the interface processes, relating the physical structure of the sensor to its electrical behavior using EIS. Electrical equivalent circuit models based on the experimental results are also presented.