A sandwich-type electrochemical immunosensor for carcinoembryonic antigen based on signal amplification strategy of optimized ferrocene functionalized Fe3O4@SiO2 as labels

A sandwich-type electrochemical immunosensor was developed for sensitive detection of carcinoembryonic antigen (CEA) by using ferroferric oxide@silica–amino groups (Fe 3 O 4 @SiO 2 –NH 2 ) as carriers and gold nanoparticles–graphene oxide (GO–AuNPs) as platform. The Fe 3 O 4 @SiO 2 –NH 2 surface was used as linked reagents for co-immobilization of ferrocenecarboxylic acid (Fc-COOH) and secondary anti-CEA (Ab 2 ) to prepare the signal probe , and it also could hasten the decomposition of hydrogen peroxide (H 2 O 2 ) to amplify signals. Differential pulse voltammetry (DPV) was successfully used to quantify CEA. Under the optimized conditions, the designed immunosensor shows an excellent analytical performance wide dynamic response range of CEA concentration from 0.001   ng   mL −1 to 80   ng   mL −1 with a relatively low detection limit of 0.0002   ng   mL −1 ( S / N =3), and high specificity and good reproducibility. The proposed immunosensor was successfully used to determine CEA in spiked human serum samples.