A novel nitrogen and sulfur co-doped carbon dots-HO chemiluminescence system for carcinoembryonic antigen detection using functional HRP-Au@Ag for signal amplification.

A novel nitrogen and sulfur co-doped carbon dots (NS-CDs)-HO chemiluminescence (CL) system was developed to detect carcinoembryonic antigen (CEA) by taking advantage of dual-signal amplification of functional Au@Ag nanoparticles (NPs) nanoprobes. Horseradish peroxidase (HRP) and the complementary DNA were co-immobilized onto Au@Ag NPs surface to shape the functional nanoprobes (HRP-Au@Ag-cDNA) for signal amplification. In this proposal, HRP-Au@Ag-cDNA was specifically hybridized with CEA aptamer-functionalized magnetic beads to form the double-strand hybridization nanocomposites (HRP-Au@Ag-dsDNA-MB). Upon the addition of CEA, the CEA aptamer preferred to bind with CEA instead of double-strand hybridization interaction, thus HRP-Au@Ag-dsDNA-MB was dehybridized and the HRP-Au@Ag-cDNA nanoprobe was released. The synergistic catalytic effects of HRP and Au @Ag NPs endow the nanoprobe producing a dual CL signal amplification in the NS-CDs-HO CL system. The CL intensity of the developed strategy enhanced with CEA concentration increasing in the range of 0.3-80 ng mL. Benefiting from the synergistic effect, a detection limit as low as 94 pg mL was obtained. Moreover, successful application of this CL sensing platform was achieved for the determination of CEA in human serum samples, demonstrating the promising prospect in the early tumor warning and therapeutic monitoring.