Abstract:A novel amperometric immunosensor for carcinoembryonic antigen (CEA) in human serum was established based on [Cu(bpy)2(ONO)]NO3 (CuL) and CEA antibody coated gold nanoparticles(AuNPs) composite film. The glassy carbon electrode(GCE) was firstly oxided and carboxyel group was formed in its surface, and then ethylene diamine was bonded to it.The ammoniated electrode was soaked in CuL and electroless gold plating solution. Then CuL can be absorbed on GCE by π-π stacking interaction and AuNPs film of 30~50 nm were formed by electroless gold plating to form GCE|CuL-AuNPs. Furthermore CEA antibody(anti CEA) was absorbed on the surface of AuNPs film with HRP employed as blocking reagent to form one CEA immunosensor(GCE|CuL-AuNPs /anti CEA-HRP). CuL can be employed for catalytic activity detection of carbamide peroxide (CP), HRP could enhance the sensitivity of immunosensor. After the immunosensor was incubated with CEA solution at 37 ℃ for 30 min, the electron transfer access of CuL to CP was partly inhibited, which lead to a linear decrease of the catalytic efficiency to CP in pH 6.5 phosphate buffer solution (PBS), the decrease percentage of current had a linear relationship with the concentration of CEA between 0.1 and 80 ng/mL. Under optimal conditions, the detection limit for CEA is 0.052 ng/mL at 3 times noise. This method simplifies the detection system without adding electron transfer media to solution with high sensitivity, wide detection range.It would be valuable for clinical immunoassay of CEA in patients’ serums.