Ultrasensitive immunosensor for detecting CEA based on double amplified signal of graphene loaded CoFe2O4/Ag nanoparticles

Using Ag-CoFe 2 O 4 -GO nanocomposite as biosensor interface, a novel unlabelled electrochemical immunosensor was designed to detect tumour marker carcinoembryonic antigen. Here, Ag-CoFe2O4-GO was synthesized by one-pot method as an immunological probe. They have the following advantages: (1) Silver nanoparticles have a strong redox capacity under applied voltage and good biocompatibility, so they can bind more antibodies; (2) GO has a large specific surface area, which can load more Ag NPs and CoFe 2 O 4 nanoparticles, and has excellent conductivity; (3) CoFe 2 O 4 is widely favoured by researchers due to its advantages such as low production cost and simple preparation process, The prepared Ag-CoFe 2 O 4 -GO nanocomposite can amplify the electrochemical signal; (4) The presence of GO can effectively prevent the agglomeration of Ag NPs nanoparticles and CoFe 2 O 4 nanoparticles, promote the formation of electron transfer network, and contribute to the electron transfer of sensors. Under optimal condition, the current signal and the concentration of carcinoembryonic antigen were linear in the range of 1 pg mL < sp > −1 < /sp > ∼ 80 ng mL < sp > −1 < /sp , > and the detection limit was 0.3 pg mL < sp > −1 < /sp > (S/N = 3). Under certain conditions, the manufactured immunosensor has good reproducibility, selectivity and excellent stability. Thus it has certain clinical value for the detection of carcinoembryonic antigen.