ZnO flower-rod/g-C₃N₄-gold nanoparticle-based photoelectrochemical aptasensor for detection of carcinoembryonic antigen

A highly sensitive and selective photoelectrochemical (PEC) aptasensor was constructed for carcinoembryonic antigen (CEA) detection based on ZnO flower-rods (ZnO FRs) modified with g-C₃N₄-Au nanoparticle (AuNP) nanohybrids. The nanohybrids of g-C₃N₄-AuNPs can improve the visible light absorbance of ZnO FRs and enhance the PEC property. We designed a sandwichlike structure formed with DNA hybridization of NH₂-probe1, CEA aptamer, and CuS-NH₂-probe2 to detect CEA. The p-type semiconductor CuS nanocrystals (NCs) at the terminational part of sandwichlike structure work as electron traps to capture photogenerated electrons and consequently lead to a magnified photocurrent change. The results indicate that the photocurrent is increased when CEA antigen (Ag) is introduced. Since the sandwichlike structure is destroyed, CuS NCs are restricted to capture photogenerated electron. The PEC aptasensor for CEA determination is ranged from 0.01 ng·mL^-1 to 2.5 ng·mL^-1 with a detection of 1.9 pg·mL^-1. The proposed aptasensor exhibits satisfactory PEC performances with rapid detection, great sensitivity and specificity. Specially, this PEC aptasensor shows a reliable result for the determination of CEA in invalid human serum compared with the ELISA method. The designed aptasensor may provide a new idea for a versatile PEC platform to determine various molecules. Graphical abstract ᅟ.