Ultra-Sensitive Electrochemical Determination of Carcinoembryonic Antigen by a Sandwich Immunosensor Graphene Oxide (GO)-Gold Substrate and a Silver-Coated Bovine Serum Albumin (BSA)-Platinum Nanocomposite on a Glassy Carbon Electrode (GCE)

An ultra-sensitive electrochemical immunosensor for detecting carcinoembryonic antigen was prepared. Graphene oxide-gold was used as the substrate modifier of the sandwich immunosensor. The high conductivity of graphene oxide effectively enhanced the electron transfer rate. The large specific surface area of graphene and the biocompatibility of gold nanoparticles increased the number of primary antibodies. The bovine serum albumin coated silver – platinum composite was used as a secondary antibody tag to prepare signal probes. The excellent biocompatibility of bovine serum albumin increased the number of secondary antibody connections. Silver nanoparticles increased the speed of electron transfer, and platinum further enhanced electrochemical sensing capabilities by catalyzing hydrogen peroxide. The immunosensor showed good performance for detecting carcinoembryonic antigen. Under the optimal conditions, the dynamic response range for carcinoembryonic antigen was from 0.005 ng·mL−1 to 100 ng·mL−1 with a detection limit of 0.76 pg·mL−1. The immunosensor also shown high selectivity, suitable stability, and good reproducibility, which provides new capabilities for clinical carcinoembryonic antigen detection.