An Electrochemical Immunosensor For The Ultrasensitive Direct Detection Of Cea Base On A Glassy Carbon Electrode Modified With Octahedral Cu₂O-Au Nanocomposites And Staphylococcal Protein A For Signal Amplification

In this work,we use a novel octahedral Cu₂O-Au nanocomposites as signal amplifying immunosensing substrate first applied in an electrochemical immunosensor for directly ultrasensitive detect carcinoembryonic antigen?CEA?in human serum.The Cu₂O-Au nanocomposites was prepared by octahedral Cu₂O nanocrystals precursor directly covered with gold nanoparticles?AuNPs?on the surface.We utilized the Cu₂O-Au nanocomposites as a signal amplification not only because it possess large surface area and high loading capacity,but also because it display remarkable ability of catalyze H₂O₂ and excellent conductivity.For further enhancing the sensitivity of our immunosensor,we introduce the staphylococcus proteins A?SPA?for efficient capture the antibody.After prepared of the electrochemical immunosensor,experimental studies showed after the H₂O₂ was introduced into the work buffer,the electrochemical signal was derived from the catalysis of H₂O₂ by the Cu₂O-Au nanocomposites.Under optimal conditions,the designed immunosensor exhibited ultrasensitive quantitative detection of CEA from 2 pg·mL^-1 to 20 ng·mL^-1 with a lower detection limit of 200 fg·mL^-1.We propose this designed electrochemical immunosensor could provide a new method to detect tumor markers for early diagnoses in clinical application.