Specific detection of carcinoembryonic antigen based on fluorescence quenching of Au-Ag core-shell nanotriangle probe

Gold-silver bimetallic fluorescence quenching nanoprobe has been synthesized based on the gold triangular nanoplate with silver coating. In order to guarantee the specificity of the probe, surface modifications of the triangular nanoplates including carboxyl replacement, carboxyl activation and antibody connection have been carried out. The fluorescence spectral study indicates that the fluorescence intensity of carcinoembryonic antigen (CEA) could be effectively quenched by the silver coated-gold triangular nanoprobe. And the fluorescence quenching ability could be improved by optimizing the interaction time and amount of binding anti-CEA to modified nanoprobe, and the interaction time of binding CEA to anti-CEA. By using this sensing method, the CEA could be detected with an ultra low detection limit of 10   pg/mL, and the linear range spans a scope from 20 to 200   pg/mL. Interference experiment results show that the influence from the interfering proteins could be neglected in the detection procedure. And the CEA could be specifically detected by using this bimetallic triangular nanoplate probe.