Tuning the Fluorescence Quenching Properties of Plasmonic Ag-Coated-Au Triangular Nanoplates: Application in Ultrasensitive Detection of CEA

By using the fluorescence spectroscopic techniques, the fluorescence quenching abilities of gold triangular nanoplates with silver coating have been studied. Because of the surface plasmon resonance (SPR)-induced nonradiative energy transformation, the fluorescence emission intensity of carcinoembryonic antigen (CEA) could be greatly quenched by the silver-coated-gold triangular nanoplates. By comparing with the bare gold triangular nanoplates, the nanoplates with silver coating exhibit greater fluorescence quenching ability and could be further improved by increasing the coating thickness. The fluorescence quenching effect also depends on the concentration of CEA. For bare gold triangular nanoplates, the quenching ability to CEA is decreased as the CEA concentration is increased. Whereas for silver-coated-gold triangular nanoplates, the quenching ability to CEA is increased as the CEA concentration is increased. By analyzing the intensity quenching of the fluorescence peak, CEA could be detected with an ultra-low detection limit of 5 pg/mL.