Ultrasensitive electrochemical immunosensor for quantitative detection of tumor specific growth factor by using Ag@CeO2 nanocomposite as labels.

In this paper, an ultrasensitive electrochemical immunosensor was developed for the detection of tumor specific growth factor (TSGF). Reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) was used to modify the surface of glassy carbon electrode (GCE). Meanwhile, Ag@CeO2 nanocomposite was synthesized and applied as secondary-antibody (Ab2) labels for the fabrication of the immunosensor. The amperometric response of the immunosensor for the reduction of H2O2 was recorded. Simultaneously, electrochemical impedance spectroscopy (EIS) and Cyclic voltammetry (CV) were used to characterize the fabrication process of the immunosensor. The anti-TSGF primary antibody (Ab1) was immobilized onto the rGO-TEPA modified GCE via cross-linking with glutaraldehyde (GA). And then the TSGF antigen and Ab2-Ag@CeO2 were modified onto the electrode surface in sequence. Under the optimal conditions, the immunosensor exhibited a wide linear range (0.500-100pg/mL), a low detection limit (0.2pg/mL), good reproducibility, acceptable selectivity and excellent stability. The proposed sensing strategy may provide a potential application in the detection of other cancer biomarkers.