A reusable capacitive immunosensor for carcinoembryonic antigen (CEA) detection using thiourea modified gold electrode

A capacitive immunosensor based on a self-assembled monolayer (SAM) of thiourea on gold electrode has been developed. Anti-carcinoembryonic antigen (anti-CEA) was immobilized on a self-assembled thiourea monolayer (SATUM) via covalent coupling. Under optimum conditions, the decrease in capacitive signal when carcinoembryonic antigen (CEA) standard was injected could be determined with a detection limit of 10 pg ml−1 and linearity in the range of 0.01–10 ng ml−1. The immobilized anti-CEA on SATUM gold electrode was stable and after regeneration good reproducibility of the signal could be obtained up to 45 times with an RSD lower than 3.4%. Good agreement was obtained when CEA concentrations of human serum samples determined by the flow injection capacitive immunosensor system were compared to those obtained using an enzyme linked fluorescent assay (ELFA) method (P < 0.05).